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Topic: Backfiring in 2, 3 and 4th gear.

in Forum: C3 Engines

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Backfiring in 2, 3 and 4th gear. (1/3)
 5/4/23 10:30pm
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Joined: 5/4/2023
Posts: 1

Hello, my 427 is backfiring when I give it gas from 2 to 3 and 4th.  Even cruising in 4th, I give it more gas and instantly backfires.  It idles perfectly, not missing.  I check the spark plug wires and all are functioning correctly.  Could it be the vacuum system? 


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Re: Backfiring in 2, 3 and 4th gear. (2/3)
 5/4/23 10:47pm
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st george, UT - USA

1972 number matching lt-1 coupe . 2nd owner since 1980. 988, steel cities gray (firemist) 407 (red) int

Joined: 4/6/2022
Posts: 4

what type of dist ,did u just take it out of storage?,could be water in gas a clogged fil,ter, bad coi,l or cond ,really need more info what year 427, hp ,stock orig or something else,mike

Re: Backfiring in 2, 3 and 4th gear. (3/3)
 5/5/23 10:03pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
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"Backfiring"....thru the exhaust, or thru the carb? 

If thru the carb, I would first suspect a carb problem, such as the accelerator pump not working properly.

Late ignition timing could do that too, as well as cross-firing plug wires, a bad distributor cap/rotor, or worn points.


Joel Adams
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