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#15
by
maxfax
on 26 Feb, 2010 06:59
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I've done it on 3 n/a's.. I was pretty conservative with the shims, about 3 hardware store washers.. I was happy with 2 of the three, but all three showed improvement.. The one acted very similar to what your are describing Wolf..
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#16
by
8v-of-fury
on 26 Feb, 2010 10:54
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The stock governor in the Bosch VE pumps
starts to cut fuel somewhere around 2200rpm.. and by 2800rpm you are left with only 20% of the total fueling you started with. By doing this modification and essentially allowing fuel fueling (as much as the motor can take before smoking like a chimney) at and above 2500 is a huge improvement. You will govern with your foot, to you liking. Instead of having a spring assembly do it for you
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#17
by
rabbitman
on 26 Feb, 2010 13:37
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I've thought of doing this for a few years but it never made sense why it would give me more power if I'm already smoking black........I can perdy much floor it at any rpm and belch soot everywhere
.
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#18
by
wolf_walker
on 26 Feb, 2010 19:40
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I've thought of doing this for a few years but it never made sense why it would give me more power if I'm already smoking black........I can perdy much floor it at any rpm and belch soot everywhere .
I've seen this point brought up a few times and never heard an answer. I'd like to though.
Hell I just turned my full load screw back today to get down to just a tiny bit of smoke on WOT.
I swear it runs better, I found myself speeding on the way home from work on a road
I've driven twice a day for the last 6 months. In the spirit of full disclosure my pump has a lot of miles
on it and sat for a long time. I just re-sealed it and it seems to start and run and such fine, but it's got
to be tired after 300K miles that I know of. Maybe that has something to do with it?
I was very conservative shimming also. I'll have another car up and running in a few months I can try again on.
It'd be neat to hear some before and after results of a 3rd or 4th gear WOT accel from 35mph to 55mph on
flat ground or something like that. I think the A1 Bentley lists acceptable numbers, my trans isn't stock so I haven't
compared mine (also I'm afraid how far off it might be).
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#19
by
8v-of-fury
on 26 Feb, 2010 22:05
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I've thought of doing this for a few years but it never made sense why it would give me more power if I'm already smoking black........I can perdy much floor it at any rpm and belch soot everywhere .
I think the fact that you can belch black with out having done the governor mod, means that you are simply getting too much fuel to early and not enough air to make combustion happen. (??) Turning up the fuel screw (allowing more fuel to be injected) and doing the governor mod (determining when that fuel is injected) are two different fueling aspects of the pump. Do the mod, P&P the head, free up the intake and the exhaust AND turn the fuel up.. WHOA, you'll be melting some stuff easy! lol
Another train of thought one must think of, is that simply turning up the fuel screw on a stock pump is not really doing anything for performance.. its all being wasted to smoke anyway! The pump will still start to govern at 2300 and will still have cut the fuel by %80 at 27-2800rpm.. I dunno about you.. but only having idle-2300 of %100 fueling, is simply not enough.
You know when your driving your car (stock pump) and you feel the acceleration hit a wall? that's about 2500 where fueling is close to %50. THINK OF THE POSSIBILITIES IF YOU ONLY LET THE ENGINE HAVE ALL THE FUEL IT WANTS!?
It'd be neat to hear some before and after results of a 3rd or 4th gear WOT accel from 35mph to 55mph on
flat ground or something like that. I think the A1 Bentley lists acceptable numbers, my trans isn't stock so I haven't
compared mine (also I'm afraid how far off it might be).
When I do mine, along with a new head seal on it.. I will take some readings.. I'll let four butt dyno's have a go at it stock, and then gov modded, and then gov modded and intake and exhaust work. See how she turns out.
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#20
by
wolf_walker
on 26 Feb, 2010 22:43
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But, if it's smoking hard on up to redline or as close as a person get's to it, how can it not have enough fuel?
Most NA's in average condition will smoke at most any RPM with more than half or so throttle, least the dozen I've
spent any time with over the years have. If it's smoking at WOT at the top of each gear, is it still not fuelled enough?
If the governor is pulling fuel progressively more I'd expect to see a bunch of smoke up to 3000-3500rpm, then it tapering off
accompanying that "hitting a wall" feeling. Sort of like the way running out of cam feels on a gasser. I feel the wall-hitting, but
still see the smoke.
Maybe it's something more complex?
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#21
by
8v-of-fury
on 26 Feb, 2010 23:50
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Maybe it's something more complex?
Just a little bit. Fueling is fully cut (%80) by 2800rpm. 3500rpm in gear is attained very very slowly actually, as you are really only running on %20 of available fueling. Your right N/a's smoke pretty much all the time I would think because of no forced induction, and PEWNY exhaust system. It may be smoking at WOT in the top of each gear, but it is not getting the full potential out of the fuel you are blowing out the tailpipe. Just because the fuel is not being used (black smoke) doesn't mean it is adequately fueled. The fuel is injected at the wrong time in the process, pump timing will also play a big part on amount of smoke I believe.
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#22
by
wolf_walker
on 27 Feb, 2010 11:07
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I could totally believe injection time being not optimal at higher rpm's, especially on older pumps, contributing to smoking.
I don't understand how black smoke could be not adequately fueled.
Unless it's an injection time issue. Does the gov mod alter dynamic timing somehow?
Would it be more accurate to say a NA motor needs some supporting modifications to make the gov mod really effective?
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#23
by
theman53
on 27 Feb, 2010 11:28
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When I did mine to the N/A's I usually turned the fuel screw DOWN. It smoked even more with the gov mod. I did my exhaust before doing this so I don't know what it would be like with out a 2.5" exhaust. After I did a 3" pvc intake and got to turn up the fuel screw more. I had more power, tons. I could go up mast hill without shifting...
All that being said I think it does change some of the advance. I also think that instead of RPM's slowly rising and waiting for the pump to reach full advance, it climbs RPM's faster with the fuel to help the advance. It is almost feels like when you stomp the go pedal it makes the engine take the fuel and go. Before it seemed like you needed a wind or downhill to make it do that. It was the second best mod I did to the N/A. First being the pvc air intake.
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#24
by
wolf_walker
on 27 Feb, 2010 11:34
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Maybe that's the deal, turn down the overall fueling but use the gov mod to add/retain more fuel at higher rpm's?
Mine was a slug with the main spring shimmed at lower rpm's and it suddenly came back to what I'd call a normal
amount of power at maybe 3K or so. It was unproductive driving around town at light accel though unless I wound it out and
kept my foot pretty far in it.
I'll try it again one day.
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#25
by
theman53
on 27 Feb, 2010 11:43
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From what I noticed you have to take the pump top off...From the test plant they put a bunch of paint on all of the bolts holding it together. I think it is so if someone takes it apart they know. I also think it is important as a locator. You don't even have to take it completely apart, just loosen it up and the top of the pump will move *mine did at least* probably a 1/4" left to right and an 1/8" back and forth. If that happens and you don't sit it on there just as it was the fuel screw could be 2 turns off either way from where it was eventhough you didn't touch it. I wiggled mine around until it was in the middle and had to mess with the fuel screw a bunch until it seemed to be back to normal, then up it went:D
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#26
by
wolf_walker
on 27 Feb, 2010 12:50
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You know I'd not noticed that but you are probly right, I bet there is some play in there. I've re-sealed a couple of pumps and always have had to fiddle with the full load screw to find happy idle again. I'd assumed I had got it off some even with the collar still there and having marked it, but that makes sense.
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#27
by
rabbitman
on 27 Feb, 2010 13:16
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I have much to learn.........
I can accelerate easily to 4000rpm in 3rd, I don't even have to floor it, 4th takes a little longer to get there but I'm pretty sure I can also blow black at that rpm.
One thing that might affect mine is I cut the fuel stop pin off inside the IP so I think it is capable of fueling more than a TD pump.
Maybe I'll try it and see what happens, first I gotta open up the intake...........
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#28
by
maxfax
on 28 Feb, 2010 00:12
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Come to think of it, all 3 cars I did it on had exhaust and intake molestation done prior.. I did have to turn the fuel down on all three after doing the gov mod, but it may have been cranked up a bit much to begin with.....
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#29
by
NintendoKD
on 28 Feb, 2010 00:52
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this is interesting, I have been trying to discover the key component in why it is that limits the rpm's now that I know that it is not the pump or the swirl chambers, now it is the cam and valve float, great to know. This is a long time coming and a lot of hard work has gone into this, thanks guys for an excellent writeup.