Engine/Transmission (1994 - 1998) stumble and shuddering

[BLillquist]

I've got a bad stumble and loping idle since I installed 370's.

mine's a 94. its got the 160 pump

it starts getting bad starting around 1000 RPM and continues till about 1100 rpm then it goes away with increasing rpm. it runs great at highway speeds.

will larger delivery valves solve this?? I have read other posts on this problem,and some say delivery valves won't work. some say they will. I need knowlegable advice on this. what size of D valves would I need??

I know 370's with the 160 pump isn't a good combination. but there's got to be a way of getting rid of this problem, sure wish I had a 180 or 215 pump

right now, then I probably wouldn't be posting this

PLEASE ANY USEFULL ADVICE WOULD BE GREATLY APPRECIATED!!

 

[PKemp]

Where is your timing set?

Did you only install the 370's or have you put in anything else?

Have you moved the plate or the AFC housing?

Do you have a non-stock plate installed?

Inquiring minds want to know... ... ...

 

[AWray]

My truck has the stumble as well. I bumped my timing and installed my 191's and 370's at the same time and have not changed anything since. The warmer the engine, the less noticable the stumble. The stumble has never caused me any problems (yet?!?!). Hopefully it will never cause a problem.



Call Piers or whoever you bought the stuff from and see what they suggest. I should follow my own advice and call Piers (where I bought everything) to see if the stumble can be solved.

 

[K5IP]

My 95 5spd (180 pump) also has the stumble. After years of trying to figure it out, I took to to Cummins. Their explanation was that the pump rack did not engage all of the delevery valves at exactly the same time when the pump was just off idle. It is more of a pump rack position problem than a speed problem although it always seems to show up at the same 1000 to 1400 RPM range.

They indicated that it was (at least my case) not worth removing the pump and setting it all up again. Quote several years ago was about $800.

They also indicated that the anomoly was not something present once the rack engagement got past the initial stages and therefore had little effect on overall performance.

Rog

 

[BLillquist]

stumble

Yes I've had the timing bumped to 16. 5, and run a #10 plate slid all the way.