I can not get anyone to understand or figure my truck out at all. I had my truck running great, now it jerks between 1500 and 2000 rpms. Mostly just when I'm in 3rd or 4th gear low rpms, it does it bad, sometimes you hear a ping when it jerks. I have the timing set 10 degrees with spout out and it sounds like it's not in time once the spout in replaced and driving it seems to be the same way. it's hard to start when it's warm acts like timing is off. it's just seems sluggish as well. I have changed everything. So the other night i decided I am going to time it by ear, i had it running great, it still jerked a little bit but not as bad, the spark knock was kinda bad (sounded like a rod knock) checked timing with spout out after test drive and it was above 25 degrees advanced. makes no sense to me. Backed timing off and the knock went away and starts like crap again and runs like crap. i know the damper didn't slip because i took a brand new one and lined them up. so i have no idea, i really hope someone can help.

 

This may sound dumb, but did you tighten the distributor and make sure it wasn't turning on it's own?

 

yeah it's tight

 

Have you checked what timing is doing with spout plugged in at idle?

 

the timing advances like it's suppose too. about 30 degrees

 

Rev it up to 3000rpm and watch the timing with spout plugged in. It should be at full advance and be steady. If it's not steady and moves around you may have a sheared pin in the distributor. The pin that holds the gear will either wallow out or shear and cause incorrect timing that can walk the gear.

 

yeah i though i had sheard the pin as well, done exactly what you said to do. it's advances and stays there. plus i just put in a new distributer thinking the other one was the problem.

 

Any codes? Just for fun, have you checked manifold vacuum at idle, 3000rpm, free rev, and under load?

 

no codes, i have done a vac test everything was good there too. I was just hoping someone had the same issue at some point. i have had nothing but issues with this motor, i am ready to pull it and put another one in.

 

You could possibly have a fuel issue.

 

yeah, that is one thing i need to do and get a hose long enough and drive it and see what the guage reads. i know idle and reving it the pressure it good. but i don't know if it dropping when driving. But this still doesn't explain why it starts hard after its warm, more if a timing issue

 

What's your fuel pressure look like? Fuel filter? Air filter? I know it may seem unrelated but it's always possible.

 

32 to 34 Ibs, new fuel filter, new air filter

 

While driving or at idle?

 

while it's at idle