That was actually my next step Josh. Even thought about putting a fuel pressure regulator on it, even though I shouldn't have to with my carrier pump. I'm getting 7psi at the shrader valve, don't think that's the problem, but I'm up for about anything before putting an ip on it! Sorry for jacking your thread Prototypemech.

 

Hairy and Josh; I'm not trying to call you out on this but do you have any documentation that this is how it works? The way I see it, just like a gas engine, the fuel needs time to burn which is why the timing gets advanced while increasing RPM. In my own logic, the retard-cam system is there to compensate for the increased compression ratio due to the increased displacement of the fuel being injected into the cylinder. In the driveway, the throttle is never increased enough to engage the retard-cam since there is no load on the engine.

 

I've got a 'decently working' IP, and I've played with the setting of the cam on the side.
I first adjusted it quite a ways back, such that the lever was partially activated at idle, and peaked out very quickly therafter. I then adjusted the 'base timing' back to where it should be.
I found that it worked plenty well up to about 2K. Between 2K and 2250, it got noisier and didn't gain any real power; 2000 and 2500 had about the same total power(i.e. downshift and still don't go any faster).
I made a long trip that way; wasn't too fun.

Afterwards, I pushed the cam forward quite a ways, so it would come on slightly later than stock. That, plus a good timing job and injectors firing at the same time, means that for the first time I can take my engine up to governed RPM(past 3K) without it sounding clattery and losing power.
I suspect that that requires a little adjustment when your pump gets worn, to compensate for a worn pressure-advance cam.

 

Im by no means an expert on this, but that is how i have been told and would imagine it is designed to operate. More load = less timing. You can definately add timing and gain power, but there is a fine line between gaining power and killing the engine. Easiest way to find out if youre right would be to dyno it.

What might be the best of both worlds, is have the pump pull timing the more your foot goes down, but have something to compensate for rpm. For instance a 3208 Cat has a weighted IP gear that acts like the weights in a dizzy. Faster you go, the more it changes timing.

Maybe not all that hard to do.... AND would help spool a turbo immensly, while retaining top end.

Paging Justin

 

I think the pump is supposed to do that; the internal IP pressure increases with RPM, apparently, and the difference between that and the housing pressure determines the advance cam position.
I suspect that the retard lever on the side may also have something to do with lowering lift pump output pressure as a function of increased fuel usage...

 

Macrobb is correct. Transfer pump pressure tries to increase timing; Housing pressure and hi-pressure plunger rotation tries to retard the timing. I dont know how many other diesels have a retard-cam system. Most other manufactures dont, as far as i can tell.

 

The timing is controlled based off of a pressure differential between the housing and transfer pump. You have housing pressure on one side of the advance piston, and Transfer on the other side. As the engine speeds up, transfer pump pressure increases while housing pressure stays the same, therefore advancing the cam ring, However, our pumps also have a light load servo valve in the advance piston that only allows such timing when the truck isn't under load. When the light load servo is depressed, it bypasses transfer pressure and the cam ring is retarded.

When you are driving down the road at speed, little throttle input, the timing is advanced, and you get a nice clean burn.

When you increase the throttle, the timing retards, "giving" you more torque...At least that's the idea anyway...

As you speed up under WOT, transfer pressure still tries to advance the timing as RPMs rise, but just how much is controlled by the trimmer screw on the side of the light load lever.

I personally think this setup is convoluted and would be better off with just a speed advance like the VE pumps have. Really, other than emissions (idle and light load) and maybe a bit of fuel mileage under light load, our advance doesn't do a whole lot.

 

to much pressure to the ip may have an adverse affect on timing, it did in my brothers Mohome swap.