Back fire thru carb ?
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Melting Slicks
Joined: Jul 2010
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From: SUFFIELD CT USA 2023 C8 CORVETTE UN-MODIFIED FINALIST
2023 C8 of the Year Finalist - Unmodified
Back fire thru carb ?
About 4 years and 7k miles back I put a 383 stroker in my '77. Quick Fuel 650 Brawler Carb, car runs great, about 400 HP starts at 30 degrees or 95 degrees, driveability is excellent. About once or twice a year there is a backfire thru the Carb and since I have an air filter with the element on side and top it twice started a small fire in the top of the air cleaner. I should just get a normal chrome top. My question is, is this a timing issue and what should I do?
Tech Contributor
Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
Backfire up through the carb is not a timing issue - it's a lean condition. If you do not have a choke, it probably occurs mostly when the engine is cold. If it occurs when the engine is hot, you might want to increase your squirter size on the primary side.
Lars
Lars
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Melting Slicks
Joined: Jul 2010
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From: SUFFIELD CT USA 2023 C8 CORVETTE UN-MODIFIED FINALIST
2023 C8 of the Year Finalist - Unmodified
Lars, Thank you for your response. I have the distributor re-curved per your papers and it made a significant difference. Back to the problem, it has an electric choke and usually does it on a hot start after sitting for 30 minutes or so. Never on a total cold start !
Tech Contributor
Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
The electric chokes do not sense engine temperature, and tend to close prematurely on a short shutdown: The choke will get cold and close, while the engine is still actually hot. You may be getting a flood-out condition on hot-start that could cause you some problems. Take a look at your choke plate position when the engine is still hot after a 30-minute "cool-down": Touch the throttle lever to crack the throttle open a little and see if the choke closes with the engine still pretty warm. If it does, you might need to revise your hot-start procedure and not touch the gas pedal at all during "warm-start" to prevent the choke from snapping closed.
Lars
Lars
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I ran a Holley with a electric choke for a number of years.
Lars is talking common sense here.
The electric choke runs off a heater coil that is entirely independent from actual engine heat.
It's impossible to ever get it truly "Right".
I gave up as this actually drove me mad! I went EFI.
Problem solved!
Lars is talking common sense here.
The electric choke runs off a heater coil that is entirely independent from actual engine heat.
It's impossible to ever get it truly "Right".
I gave up as this actually drove me mad! I went EFI.
Problem solved!
