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Discussion Starter #1
I just got done puting on new points, condesor, rotor and cap on my car and when i started it back up i got a backfire through the carb. so i thought the timing was just off so i fooled arouund with that for bit and that didnt help. checked to make sure all plug wires were in the right spot, tried disconnecting the vacuum advance, still backfires. so now my next guess is i have an intake valve stuck open. i put new valve cover gaskets on recently too so its possible something might have gotten in the head to cause the problem. what do guys think? engine is a stock 327/210hp 2barrel carb. any suggestions are greatly appreciated.
 

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Joe,
I think you are trying to overcomplicate it. I doubt that an intake valve just decided to stick open. More than likely, something you did is incorrect. This is of course assuming that the car was running ok before the "tune up"
I have seen bad parts plenty of times. Caps can crossfire etc. I would double check eveything before thinking the worse. Have you set the points properly, the best method is with a dwell meter. Double check the firing order, its real easy to get #s 5 and 7 mixed up and they will cause a backfire.
Hope this helps,

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md
 

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Discussion Starter #3
thanks bill i'll try to locate a dwell meter this weekend. i checked all the connections several times and put the old cap on as well. hopefully its just the points.
 

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Joe,
If you do not have a dwell meter, and you have the externally adjustable points, you can use the following procedure:
Start the car and get it warmed up.
Using an allen wrench through the distributor window...turn the point adjusting screw clockwise until the motor starts to run rough and missfire...then turn the allen wrench 1/2 turn counterclockwise. This will get you very very close to the correct dwell setting of 30 degrees. This is actually the factory method of adjusting the points when there is no dwell meter available.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md
 

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Discussion Starter #5
it was the worst. pulled the valve covers today and had a rocker arm twisted off the valve spring and bent pushrod. dont know what happened, just going to rebuild the engine now. planned on rebuilding next fall anyway. engine was last rebuilt about 12 years ago but only 15,000 miles on it since then. oh well it will keep me busy the next few months.
 

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JOE68,
I had something similar happen to my 67 Camaro w/ a 350. It just started backfiring at every rpm while driving down the road. I did all the stuff you did only to find out that the exhaust rocker arm on my #1 cylinder broke in half at the pivot point. The pushrod then shot up and put a dent in the valvecover, also bending the rod. It had me stumped for a while too.
 

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If it was an exhaust valve that had the rocker fall off, check the intake rocker stud on that cylinder. If the exhaust rocker falls off the intake valve has to open against extreme pressure. Enough to partally pull the rocker stud up.

Did you over rev the engine to cause the rocker to fall off? Perhaps a "test run"? Easy to do with tired springs.
 

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Discussion Starter #8
david, it was the exhaust valve spring. thanks for the tip on the intake stud pulling out, ill be sure to check that out.

i dont think i over reved it, only pushed it to maybe 2000rpm, no way to tell for sure though, no tach. i think its time was just up.
 
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