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someone help before i go crazy!!!!!!!!!!!!

6K views 9 replies 6 participants last post by  qkjuicedpony 
#1 ·
ok here is the deal i just built a new engine for my car it is a 10.5:1 c/r 306 with gt40 heads and an z303 cam and other small parts.my problem is this


-when i tried to start it up for the first time it would turn over and over so i thought the timing was 180 out so i re-set the timing and then i tried to start it and now all that happens is that when i turn it over it just turns and turns if i mash the gas it will backfire through the carburetor and when i left off of the ignition switch then it will backfire through the mufflers and it sounds like a bomb going off




can someone please help me this is driving me crazy
 
#5 ·
well i re-set the #1 piston to tdc and put the dist back in on #1 cylinder tried it and it did the same thing so i checked my firing order and i am using the firing order for a 302 ho engine from 86-93


do you think it could be in the timing set like maybe the cam gear could be off a tooth or so
 
#9 ·
I went thru the same thing. took me some time to figure it out, it was because I had the valves to "tight" they weren't closing all the way. That's if you have adjustable valve train. Just a guess.
 
#10 ·
well i don't have the adjustable valvetrain so i wouldn't guess that is my problem.however i did realize after further work that i was using the old 302 firing order and not the 302 ho one so im going to change it tommorrow and set timing again and see what happens
 
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