Zenith gav valve question

[ckulchar]

The float is set at 5/8". What would cause the motor to stop runing when the GAV valve is closed while the car is idling?

Thanks again
Charley

[tiger.1000]

Is this relating to Zenith Model B on a 4 cylinder car ?

[ckulchar]

1931 Zenith side bowl carb on a Model A.

Thanks

Originally Posted by tiger.1000

Is this relating to Zenith Model B on a 4 cylinder car ?

[tiger.1000]

Nearly midnight here in the UK.....I'll try to come up with something tomorrow

[jmeckel]

GAV should be about 1/2 turn open to star and idel, going down the road with an wamed up engine you may be able to shut it down. How far "open" do you have it to make it run good?

[ckulchar]

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1/2 to 1 turn max. Sometimes it idles fine at a stop. Sometimes it starts to race at the next stop.

[Jim/GA]

Sounds like a small bit of rust or other gunk finding its way into one of the main jets. Try blowing them all out backwards with carb spray and compressed air.

You should expect GAV to be open 1/4 turn on a warmed up engine and open about 1/2 turn when cold (even more when starting in really cold weather).

Set the idle speed and mixture on the carb with the engine fully warmed up and GAV open 1/4 turn.

[redmodelt]

Could be the foot throttle is hanging up and not coming all the way back. Might need lubrication or a new spring or is bent.

[jmeckel]

I agree sounds like a small piece of dirt. Or it could be a air leak between carb and manifold.

[tiger.1000]

My ModeL B Zenith suffered similar problems and I finally sent it to Dave Renner for a rebuild.

Dave is The Guru for these carburettors.

When the carburettor re-appeared in the UK I then had a different car which would drive, idle and never stall with the GAV fully closed.

Recently the carb has picked up a bit of dirt somewhere and now only drives happily with the GAV open about 3/4 turn on a warm engine.

It will idle with the GAV closed when warm but any attempt to accelerate is greeted by a struggle and an occasional backfire.

Dave Renner has suggested cleaning out the compensator and main jets followed by the Cap jet.

I've jet to pull the carb apart and give it a go.

[700rpm]

Originally Posted by redmodelt

Could be the foot throttle is hanging up and not coming all the way back. Might need lubrication or a new spring or is bent.

I agree. This would be the easiest thing to check, and therefore the first thing to check.