Back-fire through the Carb... What is the problem???

[James W.]

Upon cold start-up I get back-fire through the carb when I press the throttle. After warm up it is gone. This is on a 1965 L79 equipped Corvette with the original carb, coil, etc. I haven't checked the timing in a few years, but it was set at the original specs found in the shop manual the last time it was tuned. Plugs are correct AC heat range, plug wires were replaced in 2010 when I changed the plugs.

Any helpful comments would be appreciated.


Thanks,

James West

[Timothy B.]

Re: Back-fire through the Carb... What is the problem???

James,

My vote is for the choke adjustment, rotate the adjustment two notches toward rich on the hot air choke.

[Edward J.]

Re: Back-fire through the Carb... What is the problem???

Jim. If the car runs fine after warm-up its not likely a spark plug issue, Tim is likely on the right track, I make sure the choke butterfly closes when you depress the accelerator to floor the once. another thing is I find that if car sits to long the float bowl empties out from evaporation, which makes for long crank times when first starting, due to having to refill float bowl.

[Joe C.]

Re: Back-fire through the Carb... What is the problem???

Yes.
It's too lean.

[Frank D.]

Re: Back-fire through the Carb... What is the problem???

Agree with all of the above - and yes, recheck that timing !