Engine/Transmission (1994 - 1998) "370 stumble"

[HoleshotHolset]

Dad's truck ('98 auto 180hp pump... ) has 370's and "022" DV's in it... he said that it now has the "370 stumble" at part throttle after installing the 022's in exchange for the OEM DV's...



Seriously - What is this stumble?



Is it just a 370's thing - or do the big EDM's do it too? OR - is it the poor fill time of the 180hp pump camshaft being exaggerated by the big nozzles and big DV's? (I like that one the best... )



The stumble doesn't bother him much - but it would be nice to smooth it out if we could...



FWIW: My 160hp pump stumbles REALLY bad with 131's and seemed to smooth out a bit with 181's... but then it got bad with 022's and horribly bad with cut DV's...



Matt

 

[Jim Fulmer]

Matt, try putting the 181's back in it!



I had a bit of a stumble at 1400 rpm with my 180 pump and 191's didn't cure it nor did laser cuts.



It's like some do it and some don't, mine actually ended up being a pump balance issue with #5 barrel!



Jim

 

[HoleshotHolset]

Dad likes the 022's too much - now he has enough fuel to spool (need... ) a bigger turbo.



The 160hp pump in my '94 must be WAY out of balance in that case...



Matt

 

[RBratby]

im with you matt i just installed mine on sat. and the power is nice from what i can do with a stock trans but ihave a pretty good stumble at 1100 rpms. new trans comes next week. thanks dtt.

 

[Jim Fulmer]

It depends on were your Gov springs are set at, if there fairly tight you can back them off one click each and move that stumble to a lower RPM.



Jim

 

[HoleshotHolset]

If the governor springs were any looser on my '94 - both spring packs would fly apart.



The stumble doesn't make the truck undriveable... you just have to babysit them a bit if you want to avoid the stumble.



On a related note - Dad's truck also starts funny first thing in the morning... it always has done it too... warm or cold out. First crank - it fires, sputters (like low timing... ) and dies. On second attempt it fires and idles just fine... After the first run of the day - it's fine. Fuel lines, lift pump, strainer, fuel filter have been swapped out, and the overflow valve is new... .



Again - not the type of thing that keeps you from driving it... you just have to be aware of it.



Matt