Tuning Help!!!

[pismorat]

I cannot get my '79 truck to run right. It's a full roller 383 stroker, I have just had the carb rebuilt (clean filters), and I think its a timing issue. It runs good until I put a load on it (hard vacuum?) and it starts to miss; I can also hear the mech. advance tapping inside the cap. It won't rev like it used to either. Then coming down a hill and coasting, it backfires something fierce. Is it too far advanced or retarded? Anything else I should check? It started a while ago after I let it sit at an angle for a week, now its never been the same, please !!

 

[dominic]

I think you should change your distributor unit and your advance vacuum at the same time ,just an idea.

 

[pismorat]

I did some research online, it sounds like what I thought was the mech. weights tapping was really valve tapping...which means I have it far too advanced (pre-ignition). I'll try retarding it some tomorrow, but if I get it too far then it stumbles on acceleration.

 

[apache]

It sounds timing/ignition related,have you actually looked at the advance springs and inner dist parts as far as a spring falling off or? bushings shot and the dwell is all over the place possibly.

 

[GNERGY]

I used to have to scrape the plastic in the cap so the weights would open properly. Look in your cap, you might be able to see if they are touching on the inside.
Tarey

 

[pismorat]

Thanks, it's an HEI distributor with a MSD 6A box, so no points to worry about. I was thinking of just buying all new plugs & wires (again), along with new cap & rotor just for the hell off it. I'm going to mess with the timing more today to see if I can bring it back.

The weights & springs, last time I looked, were in good shape.

 

[dominic]

you sure your timmer gear is not off a tooth with the cam shaft,this could cause this problem,or if your firing order for your plug wires would be wrong.