Why won't it quit rattling?

[rabbitman]

This is kinda technical so I hope it makes sense......
 
Last week I changed my injector pump bushings, the only change was I used a different body. I used ALL of my old internal parts hoping the calibrations wouldn't change, right away I could tell they had....

The first thing was even though I set the timing right for idle, by ear like I always do, I could easily tell that it wasn't advancing enough at highway RPMs. It was so bad I could hardly hold 55mph on a flat road with no noticeable wind, EGTs were at 650F, normal is 450F for those conditions, if I tried to accelerate the EGTs shot up and it started smoking with very little gain in speed. I used the same timing spring and shims and didn't adjust the pressure regulator.

So I checked the pressure, my gauge vibrated pretty badly but here's the numbers: 40-45psi@1000rpm engine, 72-76psi@2000rpm engine. Same as before the pump redo. First I removed some shims from the behind the timing spring and that caused very loud clatters at idle and also the timing piston was no longer affected by the advance knob. So I retarded the timing and that quieted it.

I've messed the with timing and different shims for a week now and I can't seem to get it right.
Now it just feels funny, it smokes easy, yet the EGTs don't get as high as before.

Cold starts sound like marbles on a plate, but they go away after it warms up. It's also weaker at idle now too, I used to shift into 2nd at like 1500rpm now when I try I have to shift back down again.
Idle rpm is perfect
The only thing I can think of is that I got something in an injector since I didn't have very good covers on 'em. Injectors have 25,000 miles on 'em.

Any ideas? Thanks

[AudiVWguy]

Looks like you've covered all your bases. If driven around with the cold start lever out how does it act at low rpms? Timing with a dial indicator? Could the throttle lever be off a little? Does this have the gov mod done?
Just more food for thought.......
-JB

[jtanguay]

can two injection pump bodies be off ever so slightly that if affects the timing advance?  as in, not every pump is alike, and requires different thicknesses of shims in there?  that might explain it... i'd say try using the timing advance cover from your old pump and see if that does it, but what do i know  :lol:

[rabbitman]

If driven around with the cold start lever out how does it act at low rpms? Timing with a dial indicator? Could the throttle lever be off a little? Does this have the gov mod done?

Right now the timing piston advances past what the start lever can do so it only affects it at idle.
I haven't used a dial indicator yet, I used one about a year ago and didn't like how it sounded so I changed it and have been going by ear ever since.
I doubt the throttle lever is wrong, there were tick marks already there so it wasn't hard.
No gov mod, I don't see the point since I can make black smoke at any rpm so more would only drive up the EGTs.

i'd say try using the timing advance cover from your old pump and see if that does it, but what do i know

Yeah, there could be differences in the body's but as for using other cover I think changing the shims will have the same affect.

[jtanguay]

what if the internal pressure is out of whack? that will definitely affect timing advance.

[rabbitman]

what if the internal pressure is out of whack? that will definitely affect timing advance.

I checked it and with a bouncy gauge it's within 5psi of correct.

[theman53]

Did you have to take the pump top off? Everytime I have done that I have had to play with the big screw. Just a thought.

I did the timing advance mod and hated it, no cold start lever anymore.

I haven't successfully rebuilt injectors, but have you pop/spray tested them? Maybe it is just spraying a little different and causing you all the fits? Just guesses but maybe something will point you in the correct path.

[jtanguay]

oh another thought... did you transfer over the delivery valves from your known good pump to this one???  i'm assuming you did when you transfered the pump head (or did you?) but its always good to check.

and if i'm not mistaken, 5 psi off of internal pressure is actually quite a bit.  The internal pressure should be 43.5 Psi at 1000 RPM.  so if you're off by 5 psi thats about 21% off, which is huuuuge.

[rabbitman]

Sorry I haven't got back.

Update: I checked internal preesure with a nice liquid filled gauge today instead of the bouncy one I used before.
It's supposed to be 43.5psi @ 1000 rpm crank, anyways it was 55psi at idle! (850rpm), my gauge only went up to 60 so I couldn't rev it at all.

Before today if the engine was hot enough so the GP's didn't come on it would crank way too long and smoke since I had the pump retarded so much, about 20 seconds after it started the smoke went away and it was fine because the internal pressure would come up and compensate for the retardedness, and I had lots of shims in the advance spring to keep the marbles down at speed.

So now I have it at 30-35 @ 1000 rpm crank, and a skinny little shim and it works nice.

SOLVED! wooohuu

[Rabbit TD]

Sorry I haven't got back.

Update: I checked internal preesure with a nice liquid filled gauge today instead of the bouncy one I used before.
It's supposed to be 43.5psi @ 2000 rpm crank, anyways it was 55psi at idle! (850rpm), my gauge only went up to 60 so I couldn't rev it at all.

Before today if the engine was hot enough so the GP's didn't come on it would crank way too long and smoke since I had the pump retarded so much, about 20 seconds after it started the smoke went away and it was fine because the internal pressure would come up and compensate for the retardedness, and I had lots of shims in the advance spring to keep the marbles down at speed.

So now I have it at 30-35 @ 2000 rpm crank, and a skinny little shim and it works nice.

SOLVED! wooohuu

I'm going to have to remember this thread, probably going to need it when I put the rebuilt T/D pump back on for the 2'nd time since I rebuilt it.  It wouldn't start the first time

[jtanguay]

Sorry I haven't got back.

Update: I checked internal preesure with a nice liquid filled gauge today instead of the bouncy one I used before.
It's supposed to be 43.5psi @ 2000 rpm crank, anyways it was 55psi at idle! (850rpm), my gauge only went up to 60 so I couldn't rev it at all.

Before today if the engine was hot enough so the GP's didn't come on it would crank way too long and smoke since I had the pump retarded so much, about 20 seconds after it started the smoke went away and it was fine because the internal pressure would come up and compensate for the retardedness, and I had lots of shims in the advance spring to keep the marbles down at speed.

So now I have it at 30-35 @ 2000 rpm crank, and a skinny little shim and it works nice.

SOLVED! wooohuu

why not work to get it at 43.5 psi??? better efficiency

[rabbitman]

why not work to get it at 43.5 psi??? better efficiency

Here's how I see it, the engine revs up causing internal pressure to go up which moves the timing piston which compresses the spring which turns the roller ring which advances the timing .

You can change the advance curve by adding or removing shims to the spring, or bumping the pressure up or down.

So with say, 60psi @ 2000rpm engine, you'd have to add lots of shims or retard the pump just to keep the marbles down at idle/midrange but the piston might not ever make it to the end of it's travel due to excessive spring pressure. BTW this is what mine was doing, very retarded timing untill the pressure came up.

Or with say, 10psi @ 2000 engine you'd need to remove all shims and advance the initial pump timing a lot to get good idle/midrange without white smoke, but the top end may never advance enough due to low pressure.

The main thing is that the timing piston must be able to reach the end of it's travel @ IIRC 5000rpm engine, if it's ever going to rev that high.

So yes, the correct pressure would be good IF the correct shims and static timing were used, I have no way of knowing what shims I'm supposed to use.

I guess to best way would be to set the static timing with a dial indicator, set the internal pressure correctly, then mess with which shims to use.

I'm thinking out loud and having a hard time trying to write it the way I'm thinking it......

My problem may have started when I swapped all my pump internals over to a different body and the pressure mustuv somehow changed and when I checked it a week later the gauge I used was not accurate plus it wasn't liquid filled so it bounced pretty bad. Wow that was long enough

[Rabbit TD]

Did you have to take the pump top off? Everytime I have done that I have had to play with the big screw. Just a thought.

I did the timing advance mod and hated it, no cold start lever anymore.

I haven't successfully rebuilt injectors, but have you pop/spray tested them? Maybe it is just spraying a little different and causing you all the fits? Just guesses but maybe something will point you in the correct path.

I have a feeling you are right about the fuel screw needing readjusted if the pump top comes off for something.  I still haven't put my T/D pump back on to try it yet but I did take it apart and didn't see a thing wrong and I remember you saying about the fuel screw maby needing readjusted awhile back and I was meticulous putting it together both times and practiced on an old one first and it did squirt fuel out the delivery nozzles real good test spinning with a drill but didn't get much cranking on the engine though.  It took way longer than usual to get fuel to the injectors.  Normaly I just fill the pump, loosen the lines and crank about 20 or more sec. and it's coming out the fittings.  I wish I'd have tried that damn screw that day

[rabbitman]

Did you have to take the pump top off? Everytime I have done that I have had to play with the big screw. Just a thought.

I did the timing advance mod and hated it, no cold start lever anymore.

I haven't successfully rebuilt injectors, but have you pop/spray tested them? Maybe it is just spraying a little different and causing you all the fits? Just guesses but maybe something will point you in the correct path.

I have a feeling you are right about the fuel screw needing readjusted if the pump top comes off for something.  I still haven't put my T/D pump back on to try it yet but I did take it apart and didn't see a thing wrong and I remember you saying about the fuel screw maby needing readjusted awhile back and I was meticulous putting it together both times and practiced on an old one first and it did squirt fuel out the delivery nozzles real good test spinning with a drill but didn't get much cranking on the engine though.  It took way longer than usual to get fuel to the injectors.  Normaly I just fill the pump, loosen the lines and crank about 20 or more sec. and it's coming out the fittings.  I wish I'd have tried that damn screw that day

It helps in getting fuel to the injectors if you crank the fuel screw in and floor it.