[colbert66]

I just finished rebuilding a 1970 302 and have been trying to get it start up. When i just crank on it and adjust the timing it doesnt do anything except turn, when i pull the trottle to give it gas it keeps backfiring through the carb, it isnt the really loud explosive soundimng backfiring, it seems more like a release of alot of pressure but i know it is burning the fuel because of carbon deposits on the carb butterfly. It just keeps doing this and then for some reason sometimes it blows off my vaccum cap on the back of the carb, like really forcefully. I just have no idea what is going on with it, i have tried turning the distributor back and forth without ever getting a single cylinder to fire once. I know i am getting spark and obviosly fuel when i spray it in for sure. I just cant figure out why it wont fire!! Please help

[gtjoe]

Your distributor may be a tooth off.

[Dick]

It sounds like it might be 180 degrees out of tune.

[Champion Speed]

It sounds like the distributor is 180 out, or your have your firing order mixed up.

[rocky289]

You'll love this one.
How certain are you that the valve timing is correct?

[AmericanHorse]

open up your carb and clean it out. I had the same problem. I just rebuilt it and it ran like a champ. The problem was the float clearances were off and the needles were clogged.

[jb36jb]

like some people have mentioned, and im also responsible for the same mistake, either you got the firing order wrong, or the distributor is set 180 degrees off. firing order on that 302 should be 1,5,4,2,6,3,7,8 going counter clockwise on the distributor cap.