govenor removal

[DieselsRcool]

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.  

[Spike_TDI]

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.

[fspGTD]

Looking forward to hearing what you found, Spike!

[Dr. Diesel]

~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.

[Spike_TDI]

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.

[Spike_TDI]

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.

[fspGTD]

Thanks guys, for helping figure this out (especially Spike!)  Spike, if you get this cover thing figured out, I'll take several!  

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!  

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.  

[Spike_TDI]

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.

Because of the different styles of pumps you'll have to use the shims in the stock cover in the new cover.

[dieselpower]

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

[fspGTD]

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.

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!    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.  

[fspGTD]

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.

[fspGTD]

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...

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.

[Spike_TDI]

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.

[fspGTD]

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.

[fspGTD]

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: