I have installed a Holley double pumper early last year. it happens now twice that by turning on the engine that smoke came out of the air filter, the foam looks like grilled. The car drive well at certain speed but turns of by stopping.

Is the carb wrong adjusted only, or possibly the valves as well ?

thanks, Uli

Original Post

sounds to me like you've fouled the spark plugs and they're causing backfires

foam filter media can be very dangerous, do you have a fire extinguisher?

 

Absolutely correct- foam air cleaners are dangerous! What happens is, reversion causes a small cloud of fuel to hang above the carb throats and the foam air cleaners soaks it up. Then the slightest backfire ignites the fuel up in the air cleaner. Could be a very slightly burned valve, too much timing, a big cam or just a cold engine. And it's worse on Weber carbs because the reversion pulses  are stronger so the reversion cloud is bigger, with more fuel.  Webers do not have chokes as such- they have an 'enrichment' circuit instead.

When- not if- the gas-soaked foam ignites, the tall pot-metal aux venturis in Weber carbs melts. Molten metal runs down the short intake stacks & into the combustion chambers where the intake valves are open. The NEXT time the piston comes up in that cylinder, the molten pot-metal inside has solidified and you break a piston. Happened to me and others, even in warm sunny California. Also was common on 911 Porsches in the '70s. That's why I started carrying a fire extinguisher in all our cars.

yes, I am pretty sure this is a float level issue. I had this 2 years ago as well and it was adjusted. We will check this week the carb.

thanks, Uli

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