Where to put timing on 89-91 p-pump?

H

high toned sob

No Smoke
Joined
Jan 12, 2007
Messages
209
Hey I am trying to find specs for timing my buddy's truck. It's a 94 5 speed, but it's got a pump on it from a 89-91 medium duty truck.
I checked the plunger lift on it, he was saying that it was popping under a no-load rev. I got 8mm of lift, which brings it to 24* btdc.
NOw, I don't have any really high timing running trucks, but I put mine at 20* and his truck at 24* doesn't seem like mine was, even at 20*. I guess what i'm saying is it doesn't act like a truck with 24* of timing.
The pump will rev to roughly 3800 rpms, but def. does not fuel the whole way.
I would say that it starts to cut back around 3200. I took the gov. springs out and they look just like any other p-pump gov. springs, so i think i'm gonna put a 5000 kit in it.
Now the one thing that is really different is the delivery valves. They have like a "stem" on them. Really long, not like in the regular pickup trucks. I guess he was told by "a pump shop" that they can't be cut.
I have some numbers from the pump, but not with me. Can anyone help me with the timing? I have a feeling that the cam profile or "something" in this pump is different causing the timing to need to be set at a different number than what I'm used to.

Thanks
Mike
 
Did you happen to look at the pin in the pump while you were checking plunger lift? If you pin the pump and the engine that should get you to whatever stocking timing was on that pump. You could just set it there or advance it a tad to see if that takes care of the popping.
 
Hey Matt,
Actually, I pulled the pump to reseal the front cover. I pinned the pump and the engine then. Put the pump back on, then checked the plunger lift. It is still running the same, like the timing is retarded. When I check it, is is giving me 8mm of plunger lift.
It "acts" like the timing is too low. But I'm getting 24* when I check it. That is why I'm thinking that something is different with this pump in how it's supposed to be timed. Something about it is different cause it's got those funky DV's.
Either that or the original engine had different pistons, maybe calling for more timing?
He's had the pump on it since last year, and even in the dead of winter (10 degrees) it would fire up pretty quickly. NOt like a 24* engine...
thanks,
MIke
 
Sounds like this pump might have a different cam in it! I would time it to stock specs an then take a degree wheel an advance it a couple degrees so then you will know what you really have !
 
high toned sob said:
It's a 94 5 speed, but it's got a pump on it from a 89-91 medium duty truck.

Now the one thing that is really different is the delivery valves. They have like a "stem" on them. Really long, not like in the regular pickup trucks. I guess he was told by "a pump shop" that they can't be cut.
Click to expand...

Pump numbers would be more helpful than a general description, but from the sounds of it he has an industrial or "bus" application pump that more than likely uses the d-shape cam profile, timing-retarding plungers, and constant pressure valves rather than delivery valves.
 
pump numbers are:

0402 736 810
Injection Pump Cummins 6BT 5.9 L 190HP Cummins 3921777, 3921777RX 3919090,

this is the pump that's on the truck. Rechecked plunger lift, it is at 8mm, which i figured up to be 24*. Is there anything different with the cam or internals of the pump then a "normal" p-pump, like found on the dodges?

Thanks guys,
mike
 
high toned sob said:
pump numbers are:

0402 736 810
Injection Pump Cummins 6BT 5.9 L 190HP Cummins 3921777, 3921777RX 3919090,

this is the pump that's on the truck. Rechecked plunger lift, it is at 8mm, which i figured up to be 24*. Is there anything different with the cam or internals of the pump then a "normal" p-pump, like found on the dodges?

Thanks guys,
mike
Click to expand...

Cam is the same as a 160/175 pump (d-shape profile).
B&P's are 11mm and have timing retard notches (pickup pumps are 12mm).
Uses constant pressure valves instead of dv's.
Governor assembly is the same as a 160/175 pump for the most part.
 
Great Seth, thanks for the info.

Do you have any tips on where I should put the timing? I don't have a good understanding on the "constant pressure valves" other than the obvious of how it sounds? Do they have higher/lower line pressure to the injectors or anything?
The truck has 370 marines in it, and does not haze at idle, and actually doesn't smoke very much at all (unless of course you lug it really hard). But not like other 370's I've seen.
Does this pump take anything different for supply pressure, etc.?
Thanks,
Mike
 
Did ya'll ever get this thing timed? Interested in finding out what you set it at and the specifics.
 
You must log in or register to reply here.
Back
Top