Erratic sputtering and exhaust backfires...
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Erratic sputtering and exhaust backfires...
Hey guys, i just installed a used edelbrock 650 on my 83 f250 with a 429. the old holley blew out the powervalve and was getting horrible gas milage, but it ran smooth for the most part. anyway, right after putting on the new (used) carb, it started backfiring when coasting to a stop. it also has a sputtering problem....i took it out and beat the crap out of it for 15 minutes and then tuned the carb and timing and it idled beautifully and smoothed out nicely, so i know i have everything set right. after letting it cool down though i took it out again and it sputtered horribly at idle and lower speeds, and stuttered when lightly pushing the gas... but it would go away if i had the pedal floored or close to it. i ran it for awhile but the sputtering didnt go away. also on the last trip, i revved it up at a stop to try and cure the bad idle and after letting off the gas, it bombed the exhaust system (i swear it was louder than a shotgun) and blew my muffler wide open. im wondering if maybe the jets are sticking open letting the gas in all the time. any thoughts?
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Joined: Jul 2001
Posts: 8
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Erratic sputtering and exhaust backfires...
Check mechanical engine timing. Timing chain. Also check fuel level in carb bowls. Check intake vacuum for proper function. I had a problem once blowing power valves out due to a burnt valve. A compression test on all cylinders can find problems and rule them out. good luck
Postmaster
Joined: Mar 2001
Posts: 4,968
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From: So Cal
Erratic sputtering and exhaust backfires...
Was the used carb rebuilt? If so it might have been reassembled incorrectly.
Or you might check to make sure you don't have any vacuum leaks between the carb and the manifold, or any hoses plugged in wrong or missing.
Backfires are often caused by vacuum leaks in my experience and my clutzy carb rebuild attempts have often led me astray.
Good Luck,
Jim Henderson
Or you might check to make sure you don't have any vacuum leaks between the carb and the manifold, or any hoses plugged in wrong or missing.
Backfires are often caused by vacuum leaks in my experience and my clutzy carb rebuild attempts have often led me astray.
Good Luck,
Jim Henderson
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