Would dearly love to hear justins take on all this. Might be some over-engineering involved, happens to the best of us. Like you Mac im more for average horsepower / torque than a big number, and i think justin is too.

 

Alright, so I believe I've figured everything out and answered the questions from my first post.

When I first got my IP from Justin, it had an issue with timing 'lag' -- you'd press the accelerator and the advance would disappear(sounded really retarded), then 'catch up' a few seconds later.
I sent it back, and when I got it back later, that problem had been fixed. The housing(with serial number) was the same as my original pump, though.
I never learned from Justin what was fixed or what happened.

I'm guessing that when the shop opened it up and did whatever they did, they didn't adjust the governor quite right, and I'm sure never tested it fully on the stand. They probably assumed that "it made X CCs before, it should make it now".

The governor being short produced a couple of issues:
One, a lack of fueling; I'm thinking the fuel metering valve wasn't opening fully, at least higher in the revs once the governor started to 'push back'. It still felt stronger than the stock IP I had before, so I just thought I really needed to upgrade to a bigger pump. That a 110 CC pump just wasn't much above stock.

Two, I'm thinking it had something to do with this 'odd' issue I had where with the cold advance /on/, the pump was a bit squirrely; it wanted to 'take off' and rev /way/ up once I hit a certain spot on the throttle. With the cold advance off, it worked just fine and so I didn't consider it too much of an issue.

When I swapped the governor spring, I matched the new governor to the 'stock' governor I had. Which was probably .030-.045 longer than the one in there before. The extra length means that it is interacting with the governor plate sooner than before. This results in a higher idle at the same throttle position. It also results in pulling on the metering valve more strongly, so more power.

I've also realized(by looking at the throttle) that the throttle is not linear. The assembly is a 'cut' circle sliding in a U-shaped groove; at the beginning and end of the throttle stroke it won't have as much distance per degree of rotation as in the middle.

When I moved the idle position further 'back' in the rotation, I'm moving it closer to it's limit. Give it 1/8 inch of throttle off idle and the governor assembly will move less than 1/8" at half pedal.

This results in a more 'exponential' acceleration curve(which I think works better -- more control at low power levels/RPMs right at the beginning of travel, more power/less control in the mid range where you don't need it(the engine being under load by that time).

Also, by moving my idle further 'down' or 'back', I've stretched out the accelerator cable; I now am getting more pump throttle travel from idle to floored.

This also seems to have solved the 'takeoff' problem, probably because the area the throttle is moving in under a light load at idle is 'earlier' in the curve than it was.

Replacing my governor spring with a stock spring basically just gave me a 3600 RPM governed speed. No more, no less.

So, that's a wrap for anyone curious. I'll be linking this from the first post.

While I'm here, here's a video showing how to adjust the governor linkage in 5 minutes:

 

The pump that i had in my 79 had two issues you mentioned. The "delayed" timing, and was jumpy with the HPCA on. Did you find out specifically what caused that, and what the fix is? Thing would surge so bad when it was cold it was practically undrivable.

 

Mine surges when dethrottling, especially down hill just coasting.

 

Interesting.
Never figured this out(Justin's shop fixed it).
This, I'm not sure the underlying 'problem', but you may be able to mitigate it by following the instructions I lined out above - Lengthen the governor assembly by like .030, and then lower the idle screw. See if it helps.
I avoided the problem by running the cold advance to a switch on my dash. I'd turn it on, start it, wait for a minute or so and then flip it off; just enough for the engine to get running and smooth out, perhaps get it out of the parking spot. My 'jumpyness' didn't happen until 2K rpm, so as long as I was idling around in a parking lot or back roads it wasn't a problem.


Two things to try here. One is adjusting the governor like I suggested above, and the other is to adjust the guide pin at the back of the pump.
I would /try/ backing off the guide pin by perhaps 1/8"(so it sticks out 1/8" further) and see if that helps. I found that pushing it further /in/ made the governor respond 'quicker', preventing a pump from dying when I let off the throttle. Try it the other way and get back to me. In fact, perhaps try both ways if it doesn't fix things.
If you are worried about getting back to 'stock', just take a measurement with a pair of calipers or something, or even just count threads and take pictures.

At this point, it's experimentation time, and I'd love to hear what you guys find out.

 

Mine also tries to die letting off of the clutch when idling. I'll try it, just not sure when. We are really busy at work and it's REALLY cold here! But I'll let you know the outcome.

 

Just warm the truck up and do it when you get home, so you've got a nice hot engine to work on. Might still be a little cold, but you've got a nice hot radiator to sit on or warm those hands on.

 

Working today and have to go somewhere tonight. I'll give it a try when I can though.

 

Any news?


At this point, I got a new boost gauge. Not sure on the accuracy(it reads slightly below 0 with the engine off, but we are at 2K feet elevation), but it still goes up to about 21 PSI max.
I haven't been able to hook it up to a trailer /yet/ to see what it can really do... there's only so much load I can put on this thing unloaded trying to accelerate; I can barely get the engine spooled before it hit 70 and have to back off!

Dyno testing should come sooner or later this spring; I talked with the new local shop, and they wanted $110 for a baseline pull. Kinda expensive, so I'm not doing that now.
However, he will probably be doing a 'grand opening' discount one of these days, and, provided it's affordable, I'll get some dyno numbers out of that.

Before I do that, though, I want to rework my injectors; I have a bit of a skip/lope at idle, more than likely due to an unbalanced injector. I've got a new set of injector nozzles from R&D, ready to swap in, but that probably won't be for a couple of weeks, when I go to my parents place(with all my injector balancing gear).

Overall, though, it's still doing well. Drivability is good, and once I get on the throttle it has some definite get up and go. There's currently a little 'jump' in the throttle at low load where it'll go from 1000-1400 in the space of a hair, then continue smoothly upward from there, but this usually isn't an issue.

Now that I'm realizing the full potential of this pump, I am /so/ not regretting it! I just wish I'd seen this issue sooner.

 

Haven't touched it. Been busy and today, got this

 

Sorry I havent been around much, Ive been really busy with many things and my updates have been relegated to the FB group, simply because I can do it so easily from my phone.

In regards to this thread, I can pretty much explain exactly whats going on.

That .030" you added in length to the Min/Max is simply opening the metering valve further, allowing more fuel into the plungers at a certain RPM. Thats why it feels like it gained more down low, and the corresponding higher RPM numbers are about the same (or less), given the changes you made.

When I give the shop a certain spec to calibrate to (Lets take the RD2-110 for example), I give them what I want volume wise at particular RPM points. The 110 originally was a 110cc flat pump, but when I stopped doing the EDM work on them, I changed the calibration to reflect a little more fueling down low, while retaining a 110cc fuel rate at peak HP, and keeping things above 100cc at 3300.

The whole idea to keep fueling up was all about area under the curve (contrary to the assumptions above), it was about the most average fueling I could get, while still keeping things in the "110" range. Basically what you have done above, is increase the lower end fueling, and pull the upper end fueling down. While this works for your particular setup, it really wasnt what I was going for as a pump. The adjustments you made to the throttle throw are beyond Stanadyne throttle angle tolerance, and the whole reason there is a tolerance there, is because every vehicle is different, it wouldnt be a good idea for me to take that particular tolerance and "max" it out from me.

Basically what you have done with the 110, is what was doing with my early RD4 pump (Before I had even ever sold one, in my on the truck testing)...

Nothing wrong with tuning the pump to where it works the best for you, and I always tell everybody to tinker with the timing and whatever they need to to work the best for them. Basically all you have done is tilted the fuel curve to the right, pull fuel from the top, and add it to the bottom. It would be quite interesting to see where you have the curve right now.

 

Thanks for chipping in justin. I had to assume thats more or less what was going on, but i know slightly less about the inside of an injection pump than i do about alien abductions and who killed kennedy.

 

I hear you Harry. I've been working on diesels for several years now, but have never touched the inside of an ip. We always sent them to a reputable shop.

 

I finally got to work on my truck today. I tried backing the guide pin out, back of the pump, and it seems to run smoother but it didn't seem to help the trying to die when letting off the clutch much, if any. I'm going to try tightening in first chance I get.

 

Sounds to me like the metering valve sticking. Have you tried the ATF soaking trick? Has worked for me several times. The 88 was doing it after sitting a few years. Put in like 4x diesel kleen. Sorted it out after about 20 miles.