Timing issue

[Dilhunt]

I have a 1980 CJ5 AMC 258 i6 / 4.2l straight 6, it has been completely rebuilt from the ground up. Everything on the engine is new. Once you go to drive and shift from first to second it skips timing and backfires. My family and I have tried multiple flywheels and timing chains made sure all cylinders were gettin proper pressure but still can’t figure it out. Any ideas?

 

[TnCJ]

What distributor do you have? Original, or HEI?
The old original ignition systems are prone for problems as they age.

 

[Dilhunt]

It is the original thought about going with a MSD.

 

[Lumpy Grits]

Ck the engine at idle with a vacuum gauge.
Bet the needle is jumping around.
Gary

 

[Basod]

Is your vacuum advance connected?
If so I'd try disconnecting it and plugging at the carburetor first and see if you're having the same issue.

I finally sorted mine out over this past weekend at it was a rotor phasing issue that is apparently more common in re manufactured dizzys