Working on my Father in law's 94 NOT the truck in my sig. It has had a 215 fuel plate and a boost elbow and not much changed other than that for a long time. there has been a slight miss from 700 - 1100 RPM
recently we installed 191 DV's and 330 Marine injectors. At the time of install we found a broken delivery valve spring and replaced the whole set. The miss / shudder is still there at the same rpms, but is much more intense with the increased fueling. Any ideas on what is broken / worn, and where to look first.

 

I would check the fuel pressure from the lift pump first.

 

When you find it let us know. My 95 has a miss of sorts at the same rpm`s. Ive replaced the overflow valve,fuel lines,etc. It runs great but its there and annoying.Seems Ive read that its common.

 

Are you sure you have a miss and not a surge or hunting problem? When I moved my star wheel fuel adjustment foreward, it developed a rapid hunting in the governor at low RPM's and sounds similar to a miss. Try turning the star wheel back to tighten up the gov linkage.

 

Like most said I would check lift pump then overflow valve and then timing. seems that solved a few problems similar to what you have.. I would also check to make sure the rack is touching the plate in the right spot.
DM01

 

Infidel,

Lift pump has been replaced - with no change in symptoms

Hemi Cat,

Truck's on the road right now Ill check the starwheel when it gets back.

Dodgeman01

Overflow valve has been replaced. Timing is on my list of things to check. How is the SBC DD clutch compare to thier OFE for smoothness of engagement & pedal effort?


Thanks everyone for the ideas

Dave

 

hemi cat did your truck do this hunting problem all the time, idling, or under load?

 

Only under heavy throttle at low rpm's. under 1200 rpm. Lihgten up the throttle and it smooths out. It is not a miss on a cyl, it is the gov hunting. It only does that under that condition. All other conditions it is very smooth.

 

mine is doing the same thing when you let off throttle sound smoothes out or when you press clutch sound stops. but mine was doing this even before i moved starr wheel could i have a governor linkage problem?

 

If you have a lot of miles on it, you may have some wear in the gov linkage. I'm not too concerned with mine because I don't like putting a real heavy load on the eng at that low of rpm for any length of time.I usually shift to get the rpm's up.
If your truck is a hi miler, 400,000 + miles pulling heavy loads, you could have worn out inj lines causing secondary injections really screwing up the eng performance. You could try turning the star wheel back until the link tightens up a bit and try it again. You will probably see less smoke and a little less bottom end torque, but may smooth out your problem.