Delivery Valve Pop Pressure...

[Mike989]

I've looked all over and started a thread on Cummins Forum regarding my hard starting, white smoke billowing, conversion. I have swapped injectors and I am not loosing coolant. I bled the fuel lines more than once, and the only thing I actually haven't touched on this truck build is the injector pump and vacuum pump. I am starting to think my problem is coming from the delivery valves.

1. When I rechecked timing, I noticed that I am missing the spring seats and shims on my delivery valve springs. Could this cause what I'm seeing?

2. If I were to get those parts, what pop pressure should the delivery valves be set at?

Thank you in advance.

 

[Mike989]

1977 F-250 4x4: 1996 6BT 12 Valve, P-Pumped, 191 DV, 5x12, HX35W/HT3B, Manual 47RH with Second Gear Lockup mod, 48RE OD Pressure Plates w/68RE Clutches

 

[BigPapa]

Hard starting and white smoke are timing. I’ve read many posts like yours stating they’ve checked and double checked their timing, ESPECIALLY on conversions or builds where the pump is not original to the engine or has been messed with, but in 95% of the cases, in the end, they finally figure out that they’re doing something wrong or that there’s something wrong or different about their pump, shaft, gear, etc.

Your post says it’s a ‘96 5.9. Is it out of a Dodge truck?
Is the pump original to that engine?
Has the pump been to a pump shop? The pump could have been to a pump shop before you got it and set where it pins at, say, 20 degrees.
Is the shaft of the pump and the gear perfect? A burr or any imperfection will keep it from seating sufficiently to hold.

 

[Mike989]

Long story short, when I went to buy this truck, the CL add said it was a 1977 F-250 w/Cummins Installed. What it turned out to be was a 1977 F-250 400, that didn't run, and a pile of Cummins parts that weren't all there. It's 4 different motors blue printed together. Now, the pump did come from the same kid, but like I said, never opened it till last Sunday and although the AFC was messed with, it appeared to be in good shape. I originally set timing using TDC w/head removed and a degree wheel and pinned the pump. When I checked it Sunday, I used the delivery valve method and it was still at 16. Stock for this pump is 13.

The only reason I am thinking delivery valves is now that I know that those parts are missing, it makes sense. In a Mercedes Diesel, broken or worn DV springs can cause nailing and white smoke. Granted those aren't the same pump as a p-pump, but it might be the same issue, considering an improperly shimmed dv spring would be like a worn spring.

 

[BigPapa]

I don't think the DV washers/shims will make that much difference, if any, on your truck. When I put 181's in my '95 160 pump I was told not to use any washers. That was @ 350K miles ago.

 

[Mike989]

I don't think the DV washers/shims will make that much difference, if any, on your truck. When I put 181's in my '95 160 pump I was told not to use any washers. That was @ 350K miles ago.

Do you still have the washers and shims on top of the springs that sit up in the DV holder?

 

[Mike989]

I don't think the DV washers/shims will make that much difference, if any, on your truck. When I put 181's in my '95 160 pump I was told not to use any washers. That was @ 350K miles ago.

Do you still have the washers and shims on top of the springs that sit up in the DV holder?

 

[BigPapa]

Honestly, I can't remember. Seems I remember the springs and valve were taped in the the holders and I was careful to keep it all together when I installed them.

 

[Mike989]

I think I found it. If everyone reads the part about delivery valves, it says with me missing the spring filler piece, it almost certainly leads to injector dribble. I am only guessing that the spring filler piece has an orifice drilled in the center of it. I still can't find anything on the spring tension or pop pressure, but this is my plan. I will set the number one delivery valve with a .040 shim on the delivery valve between the spring and filler and pop test it. Then I will balance the others from that. I am guessing that will work.

https://what-when-how.com/automobile/lucas-in-line-injection-pumps-automobile/