Hi all,

I just swapped out my cam in my 70 road runner and I am now getting a backfiring through the carb. I know the usual reason are lean, vacuum leak, timing, or valve train issues.

I changed the cam without pulling the engine and when I put the distributor back in and went to fire it up I somehow ended really really advanced. It was kicking back against the starting but it ran just wouldn't idle.

So I retarded the timing and it starts up and runs fine. But if I rev up the engine it backfires through the carb. I can bring the rpms up slowly and it seems fine, but if I stab at the gas it backfires.


I have not had a chance the mess with it too much, but was looking for any tips on what to check for besides what I listed above. I will throw a vacuum gauge on it tonight also, but what should I look for on that and what will it tell me exactly.