NA pump mods?

[leprechan]

Wow that kind of sucks to hear about this now.  Would you say it has better performance the way you have it now?  There must be someway to make it function properly with the higher governor.  The nuts I used to preload the springs were about 3cm in length and made the springs pretty hard to compress.  What if I removed one of them?  Would that help to get rid of that sticky spot, but still have a slightly higher governor?  It seems like quite a few guys on the board are running altered governors on their pumps.  It would be nice to hear from them on how they dealt with this problem.  Maybe giles or Dr. Diesel could chime in somewhere.  I would really appreciate hearing a few more comments from people running modded pumps before going to the trouble of taking it all apart again.  I need it to be reliabe as its my daily driver, so I have to make it work one way or the other tomorrow.  I hope to hear from someone soon.  Oh BTW Thanks for all the help dieselpower and HIGH PSI.

Nick

[dieselpower]

my govenor is only shimmed like 1/8th of an inch and it still does it...it seems like only us two have had this problem along with fspgtd but he didnt have his govenor removed when that happened i dont think. did u try turning back the full load scew cuz that worked for me but i was in a racing mood at the time so i felt it wasn't in my best intrest to turn it back.
anyway i wish i knew what was gin on inside of my pump too so i could alter it some more and get some o more power outta it.
hope this helps some more


Mark


P.S.
i never really tested it with the screw turned out so the throttle doesnt stick so i dont know if it would be fatser or not. i would right now but my car is at my friends house. if you want to know anything just ask and if i kno i'll tell you or if i don't i'll try and test it.

[leprechan]

I haven't tried backing off on the full load screw yet, but I'll try that tomorrow.  I just wish it wasn't so challenging to make it work just right.  I'm bound and determined to get to the bottom of this though.  I've had my car down for the last 3 days and its basically the only thing I've been spending my time on.  If I find anything interesting out I'll be sure to post it here for all to see.

Nick

P.S.  Kind of funny how nobody else mentions any problems like this with their governor mod.  Maybe we did something wrong or failed to do something in addition to what we did.  Or maybe we were just born lucky lol.

[leprechan]

I tried backing the fuel screw off, but it only helped a little bit.  I thought about it some more and I think I might have it figured out.  I took the nuts out and also removed the part load spring.  I replaced the part load spring with one of the nuts which was enough to make up for the part load spring and slightly preload the main spring a little more than stock.  I have to go to the hardware store to get a hose clamp and then I can try it.  I will report back once I see how it works.

Nick

[fspGTD]

Let me get this straight: the problem you are currently trying to figure out how to fix is getting the RPMs to drop quicker when you pull your foot off the throttle, yes?

If so... I can offer you the following advise.  I've found these pumps develop this characteristic when the full load screw is turned in too much.  In fact, if you are experiencing this you are on the verge of having the RPMs not returning back to idle all (but just hanging up there... at 3000rpm or whatever under no load...  at which point I would recommend using the clutch and brake pedal to use the transmission to slow down the engine.)  This seems to just be a natural limit of the governor.  I suspect the flyweights have run out of room and are fully extended, or something is happing like that.  But because the full load screw is turned in so far, this minimum setting the governor is able to achieve is not able to move the contorl collar back far enough to drop the engine RPMs quickly enough (or even back down to idle at all.)

The only fix to this that I know of (not saying there might be something else yet to be uncovered... let us know if you find it.) is to reduce the full load screw setting to get the RPMs to drop back down quicker.  You can gain back fuel if needbe by modification to the LDA device (which is essentially a throttle stop.  So modifying it so say, the control cone moves further away from the feeler needle allows you to press down on the throttle farther.)

A2 injection pumps have an extra adjustment that is called a "residual pressure" adjustment that somehow effects this, although I'm not really sure how it works or if it would enable more fueling.

If you've maxxed out the LDA (keep in mind there is always a custom grind control cone, which combined with more throttle lever motion should give more fuel) and have the full load screw turned in to the verge of the RPMs not naturally falling back down on their own, I think you're just at the fueling limit of the pump at least as far as I know how to adjust them while maintaining driveability.  The next stop for more max fueling might be a 10mm plunger or perhaps a larger injector orifice size, or both.

[leprechan]

Thanks for the info.  My pump has the atmosperic thing on it, I was wondering if any of the control cone mods would give me more performance.  I'm not quite sure being that I have an NA.   Hope to hear from you soon.

Nick

[fspGTD]

Lemme think on that question... I have an atmospheric control LDA cover sitting in my garage I'd need to take another look at to answer that.

I can tell you that the ATM limiter operates very similar to boost enrichment devices (also known as LDAs.)  For sure, since they are just a fuel limiting device (like LDAs) simply removing them (IE: replacing the governor cover with a bare, non-ATM, naturally aspirated style cover) would remove the way that they limit the fuel quantity.  But... there might be a way to adjust them for more fuel too... let me get back to you on that.

What are your EGTs - juat realizing now that you've got a NA motor, I've got to ask: are you concerned about overcooking your EGTs are melting pistons by running too much fuel?  While it has been tested and shown that a big-exhausted, intercooled TD seems to have a large margin of safety in terms of being capable of having more fuel added while keeping EGTs safe and nothing from melting, an NA motor (unless cammed, ported, etc - something to add more air or reduce EGTs...) would have relatively little safety margin, IE: adding just a little more fuel may cause critical EGT levels.

I would recommend being careful about overfueling, and consider installing a pyrometer if you haven't already so you can see what's going on!

[leprechan]

Well I got it to work finally.  Replacing the intermediate spring with something solid seems to work pretty well.  It drops rpms a lot quicker than it did, but it still drops them slower than stock.  I think I just need to mess with the fuel screw a little bit more.  It doesn't seem to stick anymore and it idles fine now too.

FSP I ran the car for a while with elevated fuel levels smoking all over the place, but that quickly got old leaving a cloud everywhere I went so I turned it down where there is only a little bit of smoke at wot.  I will adjust the fuel until I can get close to that level again.  BTW how would I go about adjusting the lda to reduce fueling?  Thats something I haven't messed with yet.  I hope to hear from you all soon.  I'm gonna go play with it some more and take it for a test drive.

Nick

[leprechan]

Well the test drive went ok, but I definitely need more fine tuning.  Power was great in the high revvs.  I could peal the tires with ease in first.  The only problem now is getting the revvs to drop at a quick enough rate.  The revvs also raise quite a bit faster than they did before.  Temperature was at the same level as it normally is, though I didn't get to do much hard driving because I had to shift so low.  If anyone has any ideas my ears are open.

Nick

[leprechan]

I tried reducing the fueling, but I had to reduce it so far it would almost die on a launch from first.  I'm not really sure how to modify the lda cone for more fueling and I didn't want to drive it the way it was so I put the governor back to stock.  I would like to get it to work eventually, it just looks like that won't be until I learn a little more and have another free weekend.  Unfortunately  while tightening the cover down I rounded one of the allen bolt heads.  Next time I get to work on it I think I'll replace them all.  If someone could explain the how to modify the lda or post a link that would be great.  Well I gtg get smarter lol.  Thanks in advance.

Nick

--edit--
Hey FSP when you talked about modifying the lda for more fuel did you mean just turn the torx with the locknut on top of the pump?  If thats all I had to do I really feel stupid now lol.  I took the pump apart three times this past weekend.