Classic Engine Tech 1967 - 1981 Engine Related

car backfired under start up, now misses under load

Old 11-10-2010, 08:34 PM
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car backfired under start up, now misses under load

84 camaro. 400 small block. Sportsman 2 heads. Victor Jr. Intake. Summit 1108 cam. HEI dizzy. Long Tubes. Holley Black Electric Fuel Pump. Holley 750 DP. 4.5 power valve,about 9psi of vacuum at idle. T5 Tranny. Fuel pressure at 7psi. Need to know anything else just let me know.

So I parked the car with no problems. Came 2 days later to start the car, and it started backfiring like crazy. It cleared out for the most part, but when driving it you can almost feel a small miss but under heavy acceleration it backfires some and what i think may be it missing sometimes worse than others and just doesnt seem to have the power it did. Now you can start it and it doesnt backfire or anything but its still having the misfiring problem it seems. Things iv tried are: 2 different coils,shut the lights off with the car running and saw no arcing, plugs have the blackness to them where you can tell the car was running rich..even though it acts as if its leaning out the more i lay into it.

Any ideas?
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Old 12-27-2010, 06:23 PM
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Re: car backfired under start up, now misses under load

you blew the power valve with the backfire.
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Old 12-31-2010, 09:05 PM
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Re: car backfired under start up, now misses under load

You really need to update the post. U r killing me
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