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Engine Specific Info and Questions => IDI Engine => Topic started by: dieselpower on June 05, 2004, 08:31:34 pm
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hey,
how do I remove the govenor in my pump? I know yoou have to remove the spring and replace it with something solid but how do I actually access the spring. does anyone have pics of this being done?
thanks fo the help
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I too, am interested in removing the governor, and perhaps some of you generous pro's out there could give some hints as to what other free/extremely cheap power upgrades a poor highschool student like myself could perform.
(I have an '81 Rabbit)
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The place to start is by stuying this thread (http://www.hostboard.com/cgi-bin/ultimatebb.cgi/ubb/get_topic/f/4037/t/242) from our old forum.
That having been said, it is clear from your posts that you are not too familiar with these engines. If you go nuts and blow up your engines, may a pox be upon you! (That's old timey talk for, it's your own fault!) ;)
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I would summarize by saying, bottom line it is proven to be a good thing for getting much more usable powerband and thickness in the power curve at higher RPMs by getting rid of the intermediate spring, which makes the revv-limiter more quicker-reacting by leaving only the lower spring rate main governor left behind. (Lower spring rate = quicker rate reduction of fuel.) And, the main spring can be effectively shimmed to have its pre-load force increased, which will increase the RPMs at which it starts to limit fuel, thereby "raising the revv limiter." Also, throttle linkage (easily modified without needing to open the pump) can be modified (basic idea is to get the input shaft to rotate more at full throttle pedal travel) to also increase the RPM at which the revv limiter acts.
Disabling completely the revv limiter is more of an experimental modification. As no one knows what would happen if you were to accidentally give an engine too much throttle with too little load, how much RPMs it could safely take. Keeping the revv limiter, but just increasing the RPM at which it kicks is proven however. I've revved mine up to 6000rpm and there is someone with a 1.9lTD who posted a G-tech dyno plot of his showing he hit 6500rpm. Those are the highest numbers I have heard so far. Exceed at your own risk (and let us know when you do what happens!)
I will add that at an autocross today I stayed at the revv limiter in 2nd for a few seconds on one run (I wasn't watching RPMs when I did it, but I'd say it was probably in the upper-5000 rpm range, possibly at or above 6000 during that duration) It resulted in excessive crankcase pressure being built up, enough to blow the felt/o-ring type seal at the base of the dipstick tube, where it goes into the engine block, up around the dipstick tube about an inch. Some oil came out from that opening and covered the bottom of the oil pan, but not a large quantity. This is despite having an "open to atmosphere" crankcase breather vent on top of the valve cover!
Dyno testing shows that the stock dynamic timing advance is good to at least 5500rpm (measured on an '84 Jetta 1.6lTD) but more timing advance may be necessary in the 5750-6000+ rpm area.
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I'm not going to say too much here, because I don't remember the exact numbers, and Giles is away on vacation till june 18th. But, I believe that the advance mechanism actually stops advancing at a significantly lower rpm that what you'd expect. There is a considerable gain to be had beyond this point by having the advance mechanism modified. Replacing/modifying the max speed govenor spring is only half the battle.
(but definitely far better than nothing)
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I would love to hear more about when the timing advance is running out, and I would be very interested in coming up with a "bolt on" sort of mod that could allow it to be increased, if that were possible.
When I had my injection pump out to change motors mounts last, I did a little experimentation with the timing advance, by removing the timing advance cover and checking out the mechanism. I could see that the plunger/piston would move outwards when the cold start lever was rotated. And then the piston it could be pushed back after the cold start lever was rotated back to non-cold start position. I also tried testing how far out I could pull the piston with a little makeshift tool I inserted inside it to try and grab it from it's inside diameter and pull it out more. I was not able to get it to come out past where the cover would have blocked it's range of motion. It could have been because I didn't rotate the input shaft though, maybe there were those 4 plunger lobes/rollers inside the pump blocking the rotation of the timing mechanism. So it was not clear whether or not extra travel could be gained by bolting on a custom cover that would allow more piston clearance.
Also, dyno testing I have done confirmed at least for my pump and injectors, that timing was optimum when set at 1.00mm all the way up to 5500rpm. At 5750 rpm there was possibly a small power gain with the higher advanced setting. In particular, 1.17mm (as much as I could rotate the pump) showed a slight benefit over 1.10mm, which was equal to 1.00mm. However, I wasn't sure if it was a real gain or possibly due to operator error (early lift of the accelerator at the end of the dyno run.) The dyno measured in 250rpm increments and 5750 was the highest that it measured. But I can say with confidence that 1.00mm stock timing setting was optimal up to and including 5500rpm. Now this is for my setup of an '84 Jetta Turbo-Diesel injection pump (with modded governor) with 1.9lTD 2-stage injectors. It could be different for different pumps and/or injectors combinations.
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Edit: let's try and research if a custom timing advance cover could improve the timing much. If it might be helpful, I might be able to design and get a batch of them CNC machined but initial cost is high (It's at or above $100 and that cost doesn't seem to matter how many are made!) so the cost per unit goes down dramatically if we were to have a number of them made. But I would have to be smart in the deisgn so I don't have 100 non-useful covers made up. :?
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Can't similar effect be gained by just runnung more advanced timing? By advancing the pump to say 1.25 static wouldn't it be the same as getting .25 more advance at "all in" on the timing advance device? Only down side is you would be running .25 too advanced on the lower part of the advance curve. Maybe a noiser idle.
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At 1.17mm, the engine ran rougher, seemed to smoke more at part-load, sometimes backfired or reverse-fired or something awful like that when starting (no need to pull out the cold start knob - also I sure wouldn't recommend using spray ether with this much advance setup ever!) I really didn't like that whole starting backfiring thing. But, it did work OK like that for power (IE: it didn't hurt power anywhere running that much, but only helped slightly at highest rpm measured, 5750rpm.) I actually drove to Topeka Kansas and raced at nationals in 2003 with my injection timing set at 1.17mm. But now it's back to 1.00mm and it's much happier (I would have set to to 1.00 for nationals too but just left it at 1.17mm because I didn't have time to change it then.)
If you were to over-advance it beyond 1.17mm I'd be weay of loosing power somewhere in the usable power range. When I was dyno testing I couldn't easily try anything above 1.17mm because that's all my pump would rotate without changing the timing belt over 1 tooth on the timing belt. Dyno time was a little too precious to take the time to do that for me. But I felt 1.17 was pretty far advanced enough and woulnd't gain much testing benefit testing higher values.
In other words, it doesn't make sense to optimize your entire rpm range of timing for just one specific, very high, and not very usable rpm. But, it may have been useful to determine what rpm got helped from advancing the timing this much, if the results can be trusted which I am not 100% confident in, it might help us figure out what is happening with the timing advance mechanism. If the dyno results can be trusted, I would conjecture that the 84 Jetta 1.6lTD stock pump is limiting timing advance somewhere between 5500-5750rpm, possibly a little lower but not likely by very much.
Oh by the way the timing advance mod I am talking about above would leave the timing unchanged until the stock timing advance piston ran out of travel. It would just increase the travel that it had available. I'm not sure if it's possible with just an external pump cover swap, or if more extensive internal pump modifications are required though. It depends what exactly is limiting the travel of the timing advance piston, which I am not yet sure if it's just the cover itself or if it's something inside the pump.
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Didn't Dr. Diesel's custom pump have 3mm trimmed off the governor for this reason, or am I getting confused with something else?
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A couple of thoughts in terms of cost. (assuming that Jake is right and this will work)
1. A spacer could be used, not a complete new cover. These could be made on a digital readout mill quite easily, especially if the diamond shape wasn't critical. As I mentioned in another post, I think the Dr. Diesel trimmed 3mm on his pump. Why not make 1mm spacers so there would be some tunability? Actually, as I think about this, it gets even easier. The holes are only for clearance so you could take a stack of 1mm shims and just drill three holes through them on a crappy drill press.
2. If the cover can be round instead of diamond shaped, they can be turned on a CNC lathe in about 75 seconds per part. You would still need to drill the bolt holes though unless the lathe had live tooling.
Dropout
Edit: let's try and research if a custom timing advance cover could improve the timing much. If it might be helpful, I might be able to design and get a batch of them CNC machined but initial cost is high (It's at or above $100 and that cost doesn't seem to matter how many are made!) so the cost per unit goes down dramatically if we were to have a number of them made. But I would have to be smart in the deisgn so I don't have 100 non-useful covers made up. :?
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Dr Diesel has a small amount (less than 1 mm IIRC) shaved off the back end of his engine's injector pintals. This allows faster injection since when the injector opens less of the tip of the pintal is obstructing the injector hole. The modification is not related to timing, per se.
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That too, but I'm sure there was something with the advance mechanism. I tried the old site to check, but it's down.
Dropout
Dr Diesel has a small amount (less than 1 mm IIRC) shaved off the back end of his engine's injector pintals. This allows faster injection since when the injector opens less of the tip of the pintal is obstructing the injector hole. The modification is not related to timing, per se.
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I recall too something about that. I'm thinking he trimmed the advance piston to allow further advance.
How about putting in a 3mm spacer under the cover and then drilling and tapping the cover for an adjustable limit screw? You could then adjust max advance to your liking. Oh! How about making the cover so you can also adjust spring preload? :? How about spacing the manual advance mech so you can start at a lower static point? :shock: :?
As Jake said it all depends on if the piston can travel further.
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I have never seen a detailed explanation or write up of how either of these mods work. Only teasers that they exist! :? And I have asked how they work but no one answers.
C'mon... I share everything I know with you guys. Is that too much to ask in return?
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I don't know Jake, I'm just mentioning some ideas. I have never messed with the advance or much of the pump for that matter. I'm sure you know more than I about getting the max out of it.
If I knew any more I would certainly share. :)
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I too have ask about the timing piston mod and got no reply so I did some research for myself. I'll post what I found later tonight. Along with a CAD drawing of a new cover.
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Looking forward to hearing what you found, Spike!
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~2mm off the end of the timing piston. This requires complete pump disassembly. Maybe spacing the cover out would work. Don't forget that the piston return spring needs to maintain it's original preload.
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I compared a 10mm VW TDI pump, 11mm LandRover TDI pump, and a 9mm IDI (AAZ) pump. I don't have my book in front of me but from memory the VW TDI had 11.8mm travel, LR TDI 7.6mm, and the IDI 9.8mm. So another 2mm would put the IDI right with the VW TDI. The outer covers for both the LR TDI and IDI pump both had a 3mm recess, the TDI had 4.12mm. But because the VW TDI is electronically controlled it doesn't have the smaller piston in the middle. So using a TDI cover won't work. It also only has one spring that is a higher rate then the LR or IDI pumps main spring. So using a TDI cover won't work. The cover I drew up keeps the spring preload the same as the stock cover but add 2mm of piston travel. If I get one machined I'm going to make the recess 4mm and then use shims to set the total piston travel. I haven't had time to figure out if the compressed spring heights but I don't think that there's going to be a problem.
Laser cutting 1mm shims would also work but there might be problems with sealing and you'd have to shim both springs 2mm so the preload will be the same. Also the center stopper will also be moved back so that might cause some problems. I would really like to know what the small piston in the middle of the larger one does.
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For my own pump I'm still going to have to shave the timing piston because of it's small amount of travel right now.
(http://pics.tdiclub.com/data/500/18482adj_timing_cover_back.jpg)
(http://pics.tdiclub.com/data/500/18482adj_timing_cover.jpg)
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Thanks guys, for helping figure this out (especially Spike!) Spike, if you get this cover thing figured out, I'll take several! :D
Spike - My pump ('84 Jetta 1.6lTD) only had one plunger and one spring. Just an outer piston that was hollow in the middle with a spring sticking into it. And there were a couple precision spacers setting the preload of the spring. IMO, not having to mess with spacers... just simple, bolt-on cover, would be ideal.
I love what you are designing there with the CNC cover that keeps spring pre-load the same as the stock pump. If we get this figured out, I'll take several! :D
How did you get the piston to come out to measure how far it sticks out? Were you able to get it to come out past where it would have interfered with the cover on any of the pumps you tested, Spike?
I had trouble getting mine to come out past the point where it would have interfered with the stock cover. Did you have to remove the rear cover and push it from the back to get it to come out all the way, or could you get it to come out just by rotating the input shaft to get the cams inside to squeeze it out, or some other trick like that? If the piston is limited by something inside the pump, a bolt on cover wouldn't be enough. The pump would need to be disassembled and whatever inside there that is limiting the travel would need to be clearanced. :(
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I never pushed the piston out, I just measured the depth of the piston from the face of the pump and the depth of the recess in the cover from the face of the cover. On all the covers I could see where the piston makes contact with the cover. I haven't got around to check and see how much more the piston can extend outward. I'm going to try get to it tonight.
Both the AAZ and LR pumps have dual springs with a small piston that has some grooves cut in the backside. (http://www.photodump.com/direct/Spike_TDI/RoverPump015.jpg)
Because of the different styles of pumps you'll have to use the shims in the stock cover in the new cover.
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ok,
i decided to take a look at some pumps i had lying around and i took off the cover for a 1.6ltd and there was a very stiff spring with a washer for a spacer. if i removed the spacer it would get the same advance but quicked right? what about grinding off the bump thing that stick out in the middle of the cover? wouldnt that let the piston move more? anyway then i went to see if the 1.9l pump was the same but when i took a look at it coming off the cover was a tube type thing conected to a fuel solenoid valve. does anyone know what this does? i would post a pic but i cant figure out how to :oops:
anyway i appreciate the help so far and like the ideas you guys have
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I never pushed the piston out, I just measured the depth of the piston from the face of the pump and the depth of the recess in the cover from the face of the cover. On all the covers I could see where the piston makes contact with the cover. I haven't got around to check and see how much more the piston can extend outward. I'm going to try get to it tonight.
Both the AAZ and LR pumps have dual springs with a small piston that has some grooves cut in the backside. (http://www.photodump.com/direct/Spike_TDI/RoverPump015.jpg)
Because of the different styles of pumps you'll have to use the shims in the stock cover in the new cover.
Spike - that is a weird looking dual-piston thing you got there. Definitely not like the '84 Jetta 1.6lTD pump.
Also, just today I pulled apart the timing advance mechanism on the '85 mitsubishi pickup Turbo-Diesel diesel-kiki pump (which is just sitting in my garage. :) ) It's just got the single piston and single spring like the '84 Jetta 1.6lTD.
I also did some measuring on it. :) This one was easy to measure as it didn't have a manual cold start lever contraption on the back - just a flat block-off plate was back there. So I removed that plate. Behind there was, the back of the piston - and nothing else really interesting (no spring or anything.) I was able to push on the piston from the back to get it to move out. I found that it takes quite a bit of force to overcome the friction and get the piston to move. So this is probably why I wasn't able to get the piston on my '84 1.6lTD pump when I tried to "pull" it out.
I did some measuring on the mitsubishi pump pison travel specs:
max depth of piston: 8mm deep from front cover when pushed all the way back.
max protrusion of piston beyond cover plane: 2.5mm
So it was the cover that was limiting the max piston protrusion, and not something inside (until 2.5mm protrusion depth was reached, which seems to me like a pretty good amount!) This is very encouraging! :D If our VW VE-pumps are anything like this one I just measured, we should be able to get significant advance with just this bolt-on cover!
Spike, how long until a production run on those covers? However long you say, I have a feeling it's going to be hard for me to wait. :o
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ok,
i decided to take a look at some pumps i had lying around and i took off the cover for a 1.6ltd and there was a very stiff spring with a washer for a spacer. if i removed the spacer it would get the same advance but quicked right?
It would shift the advance curve, but wouldn't change it's minimum and maximum points (at highest and lowest rpms.)
what about grinding off the bump thing that stick out in the middle of the cover? wouldnt that let the piston move more?
No, I don't think it would make much difference. That bump just appears to be there to center the spring spacers and/or spring.
anyway then i went to see if the 1.9l pump was the same but when i took a look at it coming off the cover was a tube type thing conected to a fuel solenoid valve. does anyone know what this does? i would post a pic but i cant figure out how to :oops:
anyway i appreciate the help so far and like the ideas you guys have
Sounds like you're talking about some sort of automatic cold start device, it could be the kind that is called "KSB". I'm guessing that 1.9l pump doesn't have a manual cold start lever on the back.
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I just took another look at my dyno plots. the 1.17mm setting vs the 1.00mm setting actually made only about 1.5hp improvement at the wheels (out of about 75 hp at the wheels) at 5500rpm, which was the highest rpm recorded by the dyno.
Now, switching to the g-tech plots...
(http://www.imagestation.com/picture/sraid77/p308de5cd6daeafcbf28b813dbcb6c5f5/fb40086b.jpg)
it does seem like there is something that "kicks in" to start declining power in my hp curve at about 5200 rpm. Maybe this is the timing advance mechanism running out of travel? It will be fun to see how we can get this to change. :)
By the way, in the original 1.5lD SAE paper, there is a potentially useful engineering drawing of the timing advance plunger along with the cold start mechanism in Figure 21. And also there is a curve of crank angle advance vs engine rpm in Figure 20. The crank angle advance is 0 at about 1000rpm (with the cold start pushed in.) It then climbs linearly to about 20 crank degrees at 5000rpm, which is the highest rpm listed in the graph. (By the way, as just a side point of interest: pulling out the cold start knob moves the timing advance up to 6 degrees crank angle at all low rpms until the hydraulicly operated timing advance piston takes over at about 2100rpm.
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The bump is the stop for the small piston as far as I can see. I still want to know what the heck it's for. On the 1.9 pumps there's a valve built into the cover that delays the timing. As far as I know it allows high pressure fuel to enter the low pressure side of the timing piston. Equal pressure on both sides of the piston means that piston can't move. The TDI have a solenoid that regulates the pressure on the low pressure side of the piston to control the timing electronically.
I'm in the process of finding a shop to do a small run of the covers, I finished the toolpaths tonight. But befor ethey get machined I have to fidn out what the small piston is for and if it has to be shaved down also. My mechanical TDI pump has both pistons.
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Also, here is a plot of the 1.6lTD's timing advance specifications, from the 1.6lTD SAE Paper:
http://home.comcast.net/~vwgtd/tdsae/f40-f42.jpg (huge pic - scroll to the right to see figure 41, timing of the 1.6lTD.)
This graphs looks to be in pump or cam angles and pump rpms. It shows timing advancing from 0 pump degrees starting at about 480 pump rpm and ending at 6 degrees advance at 2250 pump rpm. No rpms higher than 2250 are listed.
Converting those to crank degrees and crank rpms (multiplying them by 2), we could have 0 degrees at 960 rpm and 12 degrees at 4500 rpm. That's a rate of change for the 1.6lTD advance mechanism of 3.39 degrees per 1000rpm. Doing a rate of change calculation for the 1.5lD gives is 5 degrees per 1000rpm. This illustrates that the 1.5l timing advances at a quicker rate than the 1.6lTD timing advance mechanism.
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Guess what? I just dropped off the timing advance cover from my '85 mitubishi VE pump at a machinist. I instructed him to take off 3mm to a 25mm diameter. (Hopefully the internal dimensions are the same as the VW 1.6lTD pump. The external dimensions look identical from what I've measured.)
This machinist is a fellow autocrosser, and has some really high tech equipment - a CNC lathe and a CNC mill. It was fun to check out his shop! The depth of the cover face "plate" was 4.5mm, so removing 3mm should leave 1.5mm of aluminum meat left for keeping the diesel inside the pump. :) If it looks too thin for comfort when I get it back, I will build up some martine-tex epoxy around the outside in the thin areas to reinforce it and add a little insurance against cracks / diesel leaks. If necessary.
I've got my fingers crossed that the 1.6lTD timing advance plunger is able to stick out past the face of the cover, like the mitsubishi pump did! I have a feeling it might. But this machining won't be too expensive (my friend is hooking me up on a deal) and it was a spare cover so I figured I don't have much to loose.
I will keep you guys updated how it turns out! I am going to have to get the G-tech set up again for doing power curve testing (setting the tachometer... getting a new download cable to download info to my new laptop would be nice, too. :) ) I might have to think about improving my crankcase ventilation system too depending how much power this adds way up high in the RPM range, I might find myself wanting to spend some more time up there! :twisted:
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if you take 3mm off the piston, or space the cover 3mm or whatever, you still need to keep the origonal preload on the spring and to do that you could put a 3mm spacer in there but it will stop the piston from moving wont it?? isnt it the actual spring that stops it from going all the way that it can? or is it the smaller piston in the middle that does the timing. cuz if its the big piston, you could just get a spring with the same preload but fewer coils so it can trvael farther. wouldn't that be easyer and cheaper than making custom cnc covers?
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if you take 3mm off the piston, or space the cover 3mm or whatever, you still need to keep the origonal preload on the spring and to do that you could put a 3mm spacer in there but it will stop the piston from moving wont it??
I agree that the spring preload should be kep the same. But if you don't change the height of the spring perch, no modification is required. The cover modification I am having done won't alter spring perch height, it is just doing some clearancing where the piston would otherwise interfere with it.
isnt it the actual spring that stops it from going all the way that it can?
Not that I am aware of. It seems like there is plenty of room for the spring inside the piston, even when it's fully compressed. Sounds like a good thing to investigate more closely and double check next time I have the 1.6lTD pump apart though.
or is it the smaller piston in the middle that does the timing. cuz if its the big piston, you could just get a spring with the same preload but fewer coils so it can trvael farther. wouldn't that be easyer and cheaper than making custom cnc covers?
You'd have to match the spring rate as well as the free length if you wanted to keep the timing advance curve unaltered before it ran out of room. Sounds pretty hard to me. But like I said, I don't think the spring is close to coilbinding. At least on the pumps I've looked at (which both lack the smaller piston in the middle.)
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Before you get him to cut it, measure the depth of the stop on your 1.6 pumps cover. My AAZ and LR were 3mm, if yours is the same then cutting 3mm is too much. So should only remove 1.5mm.
As for the spring going into coil bind it's not even close. Remember that the piston only moves 9.78mm stock. The AAZ main spring is 36mm free length, 18mm OD, 2mm wire thickness, 6 coils and 15.8mm solid length.
As for the smaller piston the only thing I can think of is that it controls the fuel pressure on the spring side of the piston. Why? I don't know maybe to make a non-linear advance curve.
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SpikeTD - What do you mean by depth of stop? Are you talking about the spring perch surface, or the little knob that sticks out in the middle of the spring? :?:
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The depth from the covers sealing side face to where the piston makes contact with the cover.
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On the cover I took off the mitsubishi pickup TD, the surface where the piston makes contact and where the o-ring seals and the bolt holes are is flush, IE: 0mm stop depth. Interesting that it sounds like there are different OEM covers available, from what you are saying.
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I just wanted to write: this is the best thread ever!
Good work Jake and Spike etc. I cannot see why this would not work, as it would be equivalent to lopping off the side of the timing piston. But, FAR FAR easier, cheaper, adjustable (potentially), and would not require new seals etc.
I am going to have a look right now at a spare pump I have around. Who knows, maybe by tomorrow I can test out a modded cover!
Jake, I can't wait to hear more about your test results :wink:
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I just went by my machinist's today. He hasn't gotten to the cover yet, he said probably next weekend. I told him not to rush (he's essentially doing it for free... and I probably won't have time to install it before then anyway.) But the good news is he did get to my vacuum pump block-off plug / oil pump thrust bearing, so I can get that in and drive my Rabbit again! It looks nice and smooth. Will be interesting to see if this gives me the extra .2 bar oil pressure I used to have when I had the vacuum pump on there.
Problem with giving this machinist something to do like this, simple, IE: "just drill a 25mm hole 3mm deep", is that the only machines they have are capable of oh so much more... all they have are 2 really impressive CNC machines, a CNC mill and a CNC lathe. I watched the CNC mill go and it changed blades automatically in like 5 seconds! And boy did the chips fly when it went at it on an aluminum bar stock. Good thing that plexiglass shield was protecting us. ;)
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Ok, I had a chance to investigate the timing mechanism on my spare NA pump. This is such an easy fix! I have the solenoid pump advance integral to the cover on this pump, but otherwise it should be the same as a standard cover.
Opening the solenoid/cover revealed two ~1.5mm disk type washers placed at either end of a very stiff red spring. Hmm timing curve adjustments! I was able to move the timing piston a bit, but chose to open the cover on the other side of the pump for maximum fun. This action allowed me to move the piston in the advanced state easily. All in all, the piston was able to protrude somewhere between 4-5mm measured with me trying to hold a dial indicator steady :? . Not a fantastic way to measure, but I can say with certainty that the stroke past the cover is way over 3mm.
Now, for the most interesting discovery: the rear plate causes a restriction, stopping the piston in the retarded direction! From the pump body, the piston was able to protrude ~1mm. So, you should be able to widen the overall timing advance curve angle by ~5mm overall! Granted, the rear plate is more difficult to remove with the pump attached to the car.
As a check, to see if the timing piston spring would return the piston *past* the rear plate, I reinstalled the front cover with the spring and the shims. Then, the rear plate was removed, and the piston moved slightly. Next, the timing lever was moved to full cold start advanced and released, and sure enough the piston protruded ~1mm past the pump body. This was exactly as before when I moved the piston by hand to full retard. I did this several times, with the same result. The piston simply prefers a final resting state past the cover. In addition, you can actually find evidence of the piston hitting the plate by observation.
Timing is everything :twisted:
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Forgive me for coming into this discussion a bit late.
First off, do the following pages aid in this discussion at all:
http://scirocco.cs.uoguelph.ca/gtd/bosch-ve/timing_1.jpg
http://scirocco.cs.uoguelph.ca/gtd/bosch-ve/timing_2.jpg
Secondly, I'm looking for a bit of clarification on the methods proposed for achiving the goal (attaining more advance at higher rpms)
(http://scirocco.cs.uoguelph.ca/gtd/bosch-ve/figure-31.gif)
The two proposed methods would be to increase the allowed travel of the timing piston (7) by either a) clearancing the cover, or shortening the overall length of the piston by removing material on the sping end, correct?
The downside to option a) would be the risk of damaging the sealing surface of the cover to the pump body - the downside to b) would be having to disassemble the pump...?
Man, this stuff is hardcore!
Drew
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There is still plenty of material for sealing the pump. One method yes requires pump disassembly, the other does not.
I was able to mod the front cover for zero dollars, and only about 30 min of my time. The pump can now advance fully, over 4mm beyond stock. I will report back later today with the results after I install the cover. For now, the rear cover will stay as is.
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I was able to mod the front cover for zero dollars, and only about 30 min of my time.
Do tell. Dremel?
Drew
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I don't have allot of time right now to reply but don't get too crazy with total timing. The total amount the the piston will move is limted by the pump case. I measured the AAZ pump the piston could only protude 6.5mm before the timing pin contacted the case. If the pin breaks your going to have some big problems. Because the cage that holds the camplate rollers is only notched so much to clear the governor asm. If it rotates too much then there going to make contact, which WILL kill the pump very quickly.
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Good point Spike. The cover has exactly enough material removed so that when the piston stops, it will actually hit the cover just like stock.
I took a few photos, and have a video as well showing the timing mechanism, but I do not have a host at the moment. Anyone?? :wink:
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Send them my way and I'll FTP them.
Advanced timing increases cylinder pressure. A bit too much and bye bye headgasket.
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I'd like to comment on the idea that the spring needs to be kept at the same installed length. Noting that the the TD has a slower advance curve than the 1.5, isn't it true that increasing the installed length by 3mm will reduce the spring tension and quicken the advance curve?
That's a good thing right?
Dropout
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Advanced timing increases cylinder pressure. A bit too much and bye bye headgasket.
It is important to distinguish between static timing and dynamic timing. If static timing (set at the pump, such as with 1.2mm) is too far advanced, then yes, the engine can suffer from excessive pressures. This can show up as low power, growly noise and blown head gaskets. Dynamic timing is the advance curve built into the pump, and typcially varies with RPM. Our diesels cap the timing at something like 20 degrees, which is in accordance with their design philosophy for these engines as lo-po econoboxes. I don't know where the max power point is, but it's got to be close to 30 degrees. Even this will result in lower peak cylinder pressures than a low RPM, high torque demand setting.
In short, I would not worry much about allowing the advance curve to extend well beyond the stock point at high RPM, so long as the static timing is set not more than about 1.1mm, based on fspGTD's posts on the subject.
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I'd like to comment on the idea that the spring needs to be kept at the same installed length. Noting that the the TD has a slower advance curve than the 1.5, isn't it true that increasing the installed length by 3mm will reduce the spring tension and quicken the advance curve?
That's a good thing right?
Dropout
The timing advance can be plotted of timing advance vs engine RPMs. Changing the spring pre-load will just shift the curve, just like changing static timing (mm plunger displacement at TDC measurement).
If you want to change the SLOPE of the curve, you'd need to change the spring rate. (Which is how much the spring collapses given a fixed amount of additional force.) This is a property of the spring itself; varying the pre-load will not change it. So you'd need to find a new spring if you wanted to change that. But this isn't what I want to do either. Dyno testing has shown at least for my injection pump / injector setup, the factory timing curve is ideal for all RPMs up to somewhere above 5000 rpm.
About that point however, although my testing is not perfectly conclusive, it suggests more timing advance would give more power. Based on my hp vs RPM plots from the G-tech, I see a sharp kink in the curve at 5200 rpm and based on hat, I am theorizing that this is where the stock timing advance mechanism stops moving, because it gets blocked by the cover. (So if you looked at the timing advance curve that showed RPMs going this high, the curve would switch from a straight, constantly increasing line abruptly to a dead horizontal line.) My goal of getting more travel out of the mechanism is keep the line straight up to a higher RPM, so hopefully it never gets to the dead horizontal area.
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Wouldn't changing the internal pump pressure via an adjustable outlet oriface change the curve also? :shock: So many variables!
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Wouldn't changing the internal pump pressure via an adjustable outlet oriface change the curve also? :shock: So many variables!
Yes it would change the slope of the timing advance curve. As would messing with the pressure-regulator mechanism that is built into the pump, screwed into the top near the pump's inlet. But neither would allow more overall advance capability like machining the timing advance piston or cover provides.
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Alright guys... I finally have got the timing cover machined now. (Long story short... Someone was going to do it for me, but they were stalling and taking forever, so I had an opportunity at my school to use their machine shop, I just took the part back and did it myself! :) ) Anyway, the dimensions of material removed from the inside of the cover are a cylinder shape with the diameter of 25mm and a depth of 3mm. Sorry for the crappy pics but hopefully you get the idea what it looks like:
(http://www.imagestation.com/picture/sraid129/p2580ca93c8900e0e283179b021f87ccb/f7cc25dd.jpg)
(http://www.imagestation.com/picture/sraid129/pce7789cad587fbce5567147e93935008/f7cc279c.jpg)
I'm looking forward to trying it out, and am going to take some before/after measurements with my g-tech pro competition accelerometer (after I get it's tachometer calibrated) so I should be able to post some before/after hp&tq vs rpm curves! Hopefully sometime this week (but maybe next week!) :)
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Looks proper Jake. Let us know how it improves the output!
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I just did a really quick and dirty calculation to estimate how much higher I might be able to revv my motor with the timing advance still working without running out of room, for the extra 3mm clearance provided by the reliefed cover. Doing a quick guesstimate for the distance from the center bore of the injection pump to the pivot point of the timing advance mechanism, I figure it might be 1.8". 3mm displacement at a 1.8" radius (arctan(3mm/1.8") gives 3.75 degrees (pump degrees.) That would equate to about 7.5 crank degrees extra advance allowed by the 3mm cover relief.
Using data taken from here:
Also, here is a plot of the 1.6lTD's timing advance specifications, from the 1.6lTD SAE Paper:
http://home.comcast.net/~vwgtd/tdsae/f40-f42.jpg (huge pic - scroll to the right to see figure 41, timing of the 1.6lTD.)
This graphs looks to be in pump or cam angles and pump rpms. It shows timing advancing from 0 pump degrees starting at about 480 pump rpm and ending at 6 degrees advance at 2250 pump rpm. No rpms higher than 2250 are listed.
Converting those to crank degrees and crank rpms (multiplying them by 2), we could have 0 degrees at 960 rpm and 12 degrees at 4500 rpm. That's a rate of change for the 1.6lTD advance mechanism of 3.39 degrees per 1000rpm. Doing a rate of change calculation for the 1.5lD gives is 5 degrees per 1000rpm. This illustrates that the 1.5l timing advances at a quicker rate than the 1.6lTD timing advance mechanism.
...(in particular, the part about the 1.6lTD timing advance working at a linear rate of 3.39 degrees advance per 1000 crank rpm) means that the 3mm-relieved timing advance cover should allow things to advance for approx 2000 crank rpm higher than stock before the timing advance piston hits the cover.
Assuming my hunch is correct that the piston hits the stock timing advance cover at approx 5250RPM, I would estimate that with the 3mm relieved cover, I should be good to go, with timing advancing at the usual linear rate, up to 7250RPM. 8)
(It is too bad I didn't get a chance to test this prior to my motor's valves getting crunched by the pistons...)
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Well there is a lot of territory in the upper-RPM area left to be tested, IMO... 5750RPM (ish) while still delivering full fuel is the highest I've had my revv limiter set to. Through dyno-testing, I found what I would describe as a limit here, or a drop-off of power, due to inadequate timing advance.
And I should correct you that we still don't know at what RPM valve float occurs on these motors. It could be 7000RPM, or it could be significantly higher. I may have revved the motor to 8000+RPM when I mis-shifted into first.
If the bottom end of my current motor is in decent enough shape, I might be inclined to use an econo-rebuild cheap-o head (maybe even just slap on a good used one...) and do further testing into the upper-RPM region. Worst case, I'd just be out a cheap-o head rebuild. I could try disabling the revv limiter completely, as well as trying out the timing advance mod.
My current motor is still behind the top FSP JH gas engines both in terms of both peak power output (although it's close) and width of powerband (means I need to do more shifting.) But I think there still may be uncharted territory in the upper RPM region worth investigating...
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are there any high preformance/rpm valve springs available for our diesels? will the ones from gassers work? because if we could eliminate valve float at say 7000 rpm and move it up to around 8000 with different springs then the only thing stopping us from revving this high would be the fact that the diesel cant burn fast enough.
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Oddly enough, the gassers often use diesel springs in heavy duty high rpm applications. Not sure how gasser aftermarket springs would compare to diesel springs.
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Another question is if the JH solid-lifter spring/lifters are the same as the solid-lifter TD head's. (I dont have ETKA anymore, so cant check...) If so, Autotech has dual sport springs that are good for 7k or so that fit the JH engines.
Worth a shot- they might be close enough to work with "minor adjustment". :)
Brendan
84 Scirocco 8v
00 Camaro L36 M49
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For '84 Rabbit, ETKA makes no distinction across different available engines, diesel or gas (EN, JF, JH, CR, JK, CY) for valve springs. This may mean that all solid-lifter VW motors got the same dual valve springs.
It lists "spring - valve, outer", part number 078 109 623A, and "spring - valve, inner" part number 078 109 633 A
Can anyone verify that a solid lifter gas engine uses dual valve spring (inner and outer?)
If so, I'd say there is a good chance that the valve springs on a solid lifter 1.6lTD would not cause float until above 7000RPM... as they do on a JH (solid lifter '83-'84 GTI 1.8l gas motor)
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Well, crap- if my car was here, I'd pop the valve cover off real quick and check. I want to say yes, because VW changed to a single-valve spring starting with the A3 8-valves. (and autotech sport springs work on all 8v engines up to 1995) After that, they sell a "conversion" kit to use their sport springs on the 95 and up engines.
So my educated guess, is yes, early 8-valves use dual springs. ;)
Anyone else have evidence to support or deny that observation?
Brendan
84 Scirocco 8v
00 Camaro L36 M49
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For '84 Rabbit, ETKA makes no distinction across different available engines, diesel or gas (EN, JF, JH, CR, JK, CY) for valve springs. This may mean that all solid-lifter VW motors got the same dual valve springs.
It lists "spring - valve, outer", part number 078 109 623A, and "spring - valve, inner" part number 078 109 633 A
Can anyone verify that a solid lifter gas engine uses dual valve spring (inner and outer?)
If so, I'd say there is a good chance that the valve springs on a solid lifter 1.6lTD would not cause float until above 7000RPM... as they do on a JH (solid lifter '83-'84 GTI 1.8l gas motor)
i think they could be over 7000 because the cameshaft of the idi is very softer than the gti.
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ok...i removed the govenor springs and it all went back together fine but during WOT the pin that slides along the cone in the lda gets pushed out and stays there....i checked out an unmodified pump i had and the same thing happens but the pin is springloaded on the unmodified pump so I can push it back in even with the throttle lever wide open. im thinking that the spring action is caused by the govenor and intermediate springs. has anyone else noticed this and does anyone think it will do any damage to the pump?
thanks for the help
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So my educated guess, is yes, early 8-valves use dual springs. ;)
Anyone else have evidence to support or deny that observation?
ALL of the 8v and 16v engines up through 95 or so had dual springs. Autotech, TT, and Crane offer replacement valve springs. I don't know where the Crane ones come from, but I have heard the Autotech ones are actually TT springs. There are some other companies out there who also offer springs, but I've had good luck with the Autotech/TT springs so far.
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hey dieselpower,
As far as I can see your situation, shouldnt the the LDA pin push the riding pin back into the pump as the LDA pin will return to its high position when no boost by its spring thus pushing the pin back into the pump by the LDA pins profile? maybe I havnt understood your problem properly or you might not understand me either :?
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yes...thats how it works, except the pin gets pushed out and stays there( i cant push it back in any way) when i am on the throttle...it just wont move and i think it will be binding against the lda cone and wreck something. the other pump i looked at doesn't do this so i don't kno if the pump is wrecked somehow or if its because of the govenor spring being preloaded soo much.
thanks for answering tho
Mark
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back in the day i had a 79 engine in a 84 4 door rabbit,,well i found out it was one of those lil 1457 engines,,i hung all the euro gti stuff on it,cam tb,intake,header,distributor,,it was like a na diesel to 4500,then it kicked ya in the arse till 7500,with stock springs,,well this went on all summer,,it loved it,,but one night i got happy doin burnouts,and it developed a rod knock at 8200 rpm,,so i limped home,and i actually ended drivin it all week to work(10 miles each way),before i swapped in another boneyard engine,,so the only thing i see holding back the diesel to rev is not the valvetrain,,its the pump,,or like someone else said,,will it not ignite fast enough at way hi revs??,,besides the stock power peak is at 4800,,so whats the sense of 8k if you have a stock cam??it wont flow up there,,i believe the power peak will remain the same place,just way higher,with turned up pump,boost etc,,deos did on the dyno a few years ago,,was like 115hp at 4600,and 139 ft pounds at 2800,,pretty close to stock peaks,,just way higher on the curve
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ok,
a little off topic but who has actually changed or removed their govenor? and how did you do it? im asking this becasue me and Leprechan shimmed both the intermediate spring and the main spring and we are haveing issues controling the revving, like the rpm's wont drop once they go high enough. anyway im just wondering if maybe i did something wrong.
any help would be appreciated
Mark
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The governor spring is required to prevent a bind at WOT between the LDA control cone and the throttle stop lever that is inside the LDA cover. If you just shimmed the governor springs solid, something could get bent.
When you press down all the way on the throttle input, the control cone feeler needle moves toward the control cone. The position of the control cone determines how far the feeler needle can move. And the distance it's allowed to move at WOT determines the fueling level. As the throttle lever is pressed down progressively, once the feeler needle touches the control cone, any further movement of the throttle lever causes the govenror spring to take up the slack. Us who have shimmed the main governor spring can feel this point as the throttle lever becomes noticeably harder to press down further. If the governor springs were removed entirely and replaced with solid linkage (like shims replacing the governor springs), then pressing the throttle down further past the point that the feeler needle contacts the control cone would either force the boost diaphgram upwards against the boost pressure so the feeler needle can move inwards (not very likely due to the narrow angle of the contorl cone and the friction of the needle on the control cone) or cause something to bend. That is why I would not recommend replacing the governor springs entirely with shims.
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back in the day i had a 79 engine in a 84 4 door rabbit,,well i found out it was one of those lil 1457 engines,,i hung all the euro gti stuff on it,cam tb,intake,header,distributor,,it was like a na diesel to 4500,then it kicked ya in the arse till 7500,with stock springs,,well this went on all summer,,it loved it,,but one night i got happy doin burnouts,and it developed a rod knock at 8200 rpm,,so i limped home,and i actually ended drivin it all week to work(10 miles each way),before i swapped in another boneyard engine,,so the only thing i see holding back the diesel to rev is not the valvetrain,,its the pump,,or like someone else said,,will it not ignite fast enough at way hi revs??,,besides the stock power peak is at 4800,,so whats the sense of 8k if you have a stock cam??it wont flow up there,,i believe the power peak will remain the same place,just way higher,with turned up pump,boost etc,,deos did on the dyno a few years ago,,was like 115hp at 4600,and 139 ft pounds at 2800,,pretty close to stock peaks,,just way higher on the curve
I found the RPM at which peak power occurs indeed increases with a modded governor on a 1.6lTD. In fact, I'm curious to see if mine increases even further as I get rid of the binding in the timing advance mechanism and increase my revv limiter even further! :twisted: Gotta get my head back on my motor first, though.
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Hey everyone, I did my governor mod tonight. I replaced the intermediate spring with a washer and also shimmed the main spring so that its half compressed. Hopefully the governor will still kick in but a lot later.
One thing I was surprised at is how much tension is required to move control arm and the force acting on the LDA pin and cone. I’m surprised that the governor pin actually has the ability to fight back against the main spring!
Now that Iv put it all back together very worried how it’s going to work. I tried to start it with some cranking but my battery went flat from using a torch to put the pump back together. I will try in the morning fingers crossed. But when it was cranking it didn’t seem that promising :cry:
I also noticed how much harder you have to push on the throttle when the pin hits the LDA cone. It comes on quite early as well, I hope that I put the throttle lever on the same position as it came off.
Hey fspGTD, did you try the modified timing advance cover you drilled? This is probably going to be next on my list if this governor mod goes successful.
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Good luck with getting the car started. I've got a couple ideas that might help: 1. full load screw position - did you re-install it carefully (IE: counting threads) so that it's in the exact same position as it was before being removed? 2. priming the fuel pump - is necessary if it lost much fuel when the pump was opened up. Usually when you lift the cover off of the pump with it installed in the car, there is just a pool of diesel fuel sitting there. If this pool stayed "topped off" when you replaced the cover, I think you won't need to prime it. But if the fuel level got below the high-pressure inlet port level, you may need to prime the pump - get more fuel inside there somehow.
On the machined timing advance cover - no I have not yet tried it. You may have heard about my little setback with the 1st gear mis-shift over-rev incident several months ago. Well the current status is, I just got a new rebuilt head installed onto the block last night, headbolts torqued, cam timed, with manifolds, water necks, and turbo installed... so it's coming along.
Another setback with my advance cover project that has just recently developed... I dropped off this cover off to get it anodized with a batch, as well as a bunch of other aluminum parts, and when the parts came back, this cover was missing. The guy handling the anodize batch is going to check a couple places when he gets home but might have lost it. :( Hope it was not left sitting at the bottom of some acid cleaner tank or something! :o
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Thanks for the reply Jake, Iv made another topic on this problem if you havnt already found it...
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Another setback with my advance cover project that has just recently developed... I dropped off this cover off to get it anodized with a batch, as well as a bunch of other aluminum parts, and when the parts came back, this cover was missing. The guy handling the anodize batch is going to check a couple places when he gets home but might have lost it. :( Hope it was not left sitting at the bottom of some acid cleaner tank or something! :o
I'd love to see this discussion continue. I don't have anything to add at the moment but I'd like to hear updates. :) A G-Tech plot showing the difference would be nice, too.
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hey,
i did the timing cover mod a long time back when i first heard about it. personally i didn't see any gains but i had no real way of testing it. if you or a friend or workplace or whatever has a metal lathe...all you have to do is stick it on there and it takes like 2 minutes to do. thats all i did anyway. but like i said..im not sure if it did anything first because i don't have a way of testing it, and second becasue with the govenor mod i did i barely take it above what rpm it used to go, it just gets there quicker. but its gettin warm out now, and i think i figured out a tach setup that might work for me, so im about to modify my govenor again, except this time go all out :twisted:
hope that helps
Mark
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A few days ago I installed a washer inside the intermediate spring so it wouldn't compress, didn't experience any difference on the performance so then I also shimmed the main spring a bit and went out for a test drive, revved it up on 1st gear and it wouldn't rev down when I was going to shift to 2nd, went back to the garage and took it apart again and removed the shims so it was back to standard again and then it started to work properly again..
why didn't it rev down?
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I've got a new timing cover to experiment with (as well as the rest of a disassembled TD pump! :D ), and interestingly, it's slightly different than my previous one. But I've gotten sidetracked trying to get my motor to start more reliably so I haven't gotten a chance to pick back up the timing cover experiments yet.
In theory, the cover should only effect RPMs that are very high at max fuel type setting. Basically, this might not matter very much for the street, but may make a difference to wring out that last bit of power on a pump with a modded governor. It is possible I suppose that it won't help at all too - but you need to be able to test this kind of thing with a dyno or RPM-sensing g-tech really, "seat of the pants" is not accurate enough.
Phredde - that is odd that shimming the intermediate spring would not make a difference, I don't understand what would explain that. In my experience, the difference is so noticeable it would be hard to miss!
Regarding your problem of the RPMs not dropping quickly enough, what's happening is there is too much fuel at "no load". Are you sure it's the result of the governor shim? Did you change the position of the full load screw? I've found that turning in the full load screw too far causes that condition and when it happens I usually end up just backing the full load screw out a bit.
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Hey guys guess what! I was fumbling around in the shop and I found my machined timing cover! :D Someone put it where I didn't expect it, I guess I never dropped it off at the aluminum anodizers after all!
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OK - time to revive this thread yet again! I made some more progress assessing the viability of the machined timing advance cover, and things are looking good.
Before installing the '84 1.6lTD injection pump on dad's Rabbit 1.6lD, I took the opportunity to remove its timing advance cover and cold-start advance lever covers, and I took some piston travel measurements. Pushing on the back side of the piston to see how far out it would go, I found that by the time something inside the pump stopped it moving out, it reached a protrusion beyond the face of the cover of about 5mm! This means that the piston of the '84 1.6lTD pump in my Rabbit GTD autocrosser should be able to move freely out at high RPMs up to the full 3mm depth I had machined into the cover, with no internal pump modifications necessary to achieve the additional timing piston travel.
I also verified that the depth of the spring perch of the machined cover I have (which actually came from a mitsubishi pickup truck) matches the cover out of the '84 1.6lTD, and the spring perch looked functionally equivalent. So I should be able to bolt this thing right on and expect it to not mess up the enitre dynamic timing curve (at least not a whole lot.)
By the way, going from memory here, IIRC the full travel of the stock timing piston was about 7mm. And also IIRC, moiving the cold start advance lever moves the piston out by about 2mm. (All figures are accurate to only about .5mm, due to crappy inaccurate plastic measuring calipers I badly need to replace! :? ) This basically confirms that a 3mm increase in the travel of the timing advance piston is a significant amount - an increase of about 43%!
Also can take away from this, that if pulling the timing out is good for a 2000RPM change in dynamic timing, at 2mm change in timing piston, that would mean adding 3mm to the end if its travel would add an additional 3000RPM to revv before the mechanism reaches it's limit.
I know a lot of you guys have been anxiously awaiting to hear the results. So now, if I just could get the GTD motor starting reliably (and finish up other projects like dad's Rabbit turbo conversion :?), so I could move on to testing this.
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My 1.9pump started to leak on the ingoing shaft for the throttle mechanism I started to get my GTD pump project going..
The idling spring was m,issing when I first opened the pump so I canibalised my 1.6NA pump for the little spring, then I noticed that the both springs are thicker and stiffer than the one on the GTD pump:
(http://www.morninglight.nl/a3/governor1.jpg)
(http://www.morninglight.nl/a3/governor3.jpg)
Upper one is the stock 1.6 GTD
I swapped the partload spring and added a washer:
(http://www.morninglight.nl/a3/governor2.jpg)
Total increased length is about 2.5mm.
ps. I just noticed that the fullload spring is stiffer too.. gonna swap that one too I think :)
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does anyone know if the governor weights are different from pump model to pump model? It would seem that a lighter governor weights would increase the powerband of the pump
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interresting photo:
on the right peugeot and vw gtd 80cv on the left.....
(http://img409.imageshack.us/img409/899/levierpompe6ju.jpg)
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This is what I did to the governor on my car when I had it apart:
(http://www.tdtuning.com/pictures/governor1.jpg)
It now revs past 5000 rpm although it is past it's torque peak by then. Between this and the 10mm pump head (for now) There was quite a difference.
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those are some great pics...are there any boost problems with the removed intermediate spring...as far as binding with the aneroid pushing down once the turbo is on boost? I have a fiat 11mm pump and it definitely needs the governor modded...power starts to cut out at approx 3500rpm
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Everything has been just fine since I got the pump adjusted properly. This took me several test drives and a little fine tuning over a couple of days of driving. I haven't played with the timing anymore, but it is at 1.2mm as that is what it took to get it to run properly with the 10mm pump head. I think this is an area where 'more is better' will probably be detremental. The springs do more than just determine where fuel becomes limited. They also smooth the operation of the engine and the transition between on and off throttle. The short of it is that you should probably only shim to get the cut-off to where you want it. Anything more will likely compromise some driveability.
As for the LDA - I had to readjust that because it would smoke really bad off boost. I can't say I've run into any issues with it binding. There is still plenty of travel in the governor assembly though
The first time i took it for a drive I turned out onto a main road and stood on it because there was a Cadillac coming. I looked in my rear view mirror to see a black cloud covering the lane behind me and drifting off toward the right lane and the median. The Cadillac quickly changed lanes. :D
This was also partly due to the timing. Smoke diminished a bit when I advanced the timing. .