Originally Posted by oldhickory
i just installed a new stock cam in my 402 bbc. i also put in a new timing chain and gears. the truck starts and throttle response is pretty good, but it sounds like its missing on one cylinder and occasionally backfires. it has backfired at the carb and at the muffler. when i installed the sprockets for the timing chain, i had the engine at TDC on compression stroke. the dots on the gears were both at 12 o'clock. i pulled the gears off and installed the new ones the same way. i used a straight edge to make sure they were aligned. i have not let it idle but i have started and stopped it a few times. i have checked and rechecked my plug wires. i have a couple of questions:
first, is it possible that i am a tooth off on the timing chain? would that cause a misfire?
second, should i break the cam in with the engine misfiring, or should i address that issue first?
If you have already started but did not follow the breakin procedure, chances are you now have a bad cam. To properly breakin a cam, you can not shut it off after starting it. You might check all of the valve adjustments and start it again, this time following the breakin procedure. You may get lucky.