[Mike Fowke]

Originally Posted by mchell

10/4

Reading your post again…. Noticed you mentioned backfire. Tough one as it could be going lean (carb) ……or ignition. Sounds Ike you ruled out valve train and cam.

A few things you probably looked at:
When’s the last time you pulled the dist. and checked the dist. gear? Try a spare dizzy? Plugs look OK? Timing coming in good, not advancing to much at wot? Do you limit dist advance?

See post 11. I think I've ruled out ignition and fuel. I didn't consider the distributor gear, but I used the same one to test the HEI. I think I would have noticed any wear. Timing is 12 initial, 30 total (recently verified). I think the MSD advance stop bushing limits total.

Tomorrow I'm going to call the machinist who fixed the heads and explain the problem. I'm sure he'll measure the springs for me, and he may want to see the heads. I'll go from there.

Thoughts and suggestions are still welcome, and I appreciate the feedback.