Why won't car start with new camshaft?

Question

I recently installed a new camshaft, lifters, and timing chain on my 78 Camaro. I followed a Chilton guide step by step for the whole process. Piston #1 at top dead center (turned crank until both lifters, intake and exhaust, on #1 cylinder were down / recessed) and Camshaft gear timing mark at six o'clock position / crank gear timing mark at 12 o'clock position. Monday night I finished re-assembling the engine but could not get it to start. The motor turns over and backfires. I tried turning the distributor (advancing timing) to no avail, only backfiring. What do I need to do?

The car is a 78 Camaro, 5.7L V8 SBC, Holley 650 cfm carb, Headers, edelbrock intake, etc. The newly installed cam is COMP with .470 lift.

done wrenching · Accepted Answer

You put the distrib in wrong, I would lift distrib up and turn rotor 180 degrees, that's 1/2 turn. Some people don't get it, that when cam dot is at 12 oclock and crank dot is at 12 oclock, THAT is when it is set to fire #1 cyl. I don't know what the heck you read, but it was wrong. When you line up the dots(cam at 6 oclock, and crank dot at 12 oclock, that is set to fire cyl #6.

bestwrencher · Answer

A backfire usually means that the sparkplug fires while intake valve is open, that could be as simple as wrong firing order with sparkplug wires or as complex as miss timed cam lobes , I take #1 cylinder plug out and crank with finger over spark hole when compression pops finger off hole then spark from plug should happen at same time, once I know I have #1 close the rest 1 8 4 3 6 5 7 2 should be easy , as for incorrect cam or lifters not set ( lifters should have been collapsed if you reused, new ones come collapsed) may have to verify cam  part number

bandit_60 · Answer

try doing it this way. i know you probably did,nt have the distributor pulled but put number 1 piston all the way up then turn the crank to where it,s on 0 then check to see where the rotor is pointing at. it should be pointing to number 1 plug wire. if it,s not then pull the distributor and drop it back in pointing to number 1. if it wont drop in then take a long screwdriver and turn the oil pump then drop it in.

Anonymous · Answer

recheck,put cylinder 1 at top dead center,exhaust and inlet valves cam lobes pointing up and away and make sure the rotor arm is pointing to cylinder one segment of the cap,this should be cylinder one on compresion/ignition.You've timed it for 6.

kjlh58 · Answer

You may have the distributor in wrong. check Google for correct installation of a GM. distributor

kelly_f_1999 · Answer

recheck your work you miss one of the steps and after you have recheck adjust higher or lower while trying to crank it

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Why won't car start with new camshaft?

6 Answers