GAV adjustment - how to

[JoeCB]

I usually run with about 1/2 turn open on the Gas Adj Valve, all seems to be OK at that setting. But is there a better way to make an optimum setting? Is there any reason to run richer (more open) after starting a cold engine?

Joe B

[J Franklin]

Set it where it runs the best.

[100IH]

There should be no effect at idle. Just as the butterfky opens it will be part of the mid range and high speed so it is changed at driving speeds. Screw it in and there will be less additional fuel= leaner. Back out the control knob and there will be more additional fuel= richer. Set it lean just short of feeling diminished performance. Just like J Franklin said.

[chrs1961815]

On my engine I run it more rich when it first starts up then close it a little bit when it warms. It works for me fine, it gave me a better idle.

[Kurt in NJ]

I used a 4 gas analyzer with the car on a dynamometer ( the New Jersey emissions tester)to figure best setting, it is different with ethanol vs regular gasoline, on my car regular gas, full closed, on ethanol 1/4 turn till 55, then 1/2 gives leanest acceptable mixture---- and the emissions could have passed for a 2000 Honda Civic

[Mike V. Florida]

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http://modelabasics.com/carb%20basics%202.htm

[BILL WILLIAMSON]

Warm the engine, run it at a constant 25 MPH in second gear & adjust the GAV for smoothest running.
Bill W.

[mike657894]

Originally Posted by Kurt in NJ

I used a 4 gas analyzer with the car on a dynamometer ( the New Jersey emissions tester)to figure best setting, it is different with ethanol vs regular gasoline, on my car regular gas, full closed, on ethanol 1/4 turn till 55, then 1/2 gives leanest acceptable mixture---- and the emissions could have passed for a 2000 Honda Civic

thank you for this dyno tested info. I have been finding some oddness with the e10.

[Purdy Swoft]

It is recommended to run the Zenith one , two and three carburetors at one guarter turn off the seat after warm up . The model B carburetors should run with the GAV closed after warm up . The aftermarket pot metal carburetors usually need to run a little richer because of possible warpage and vacume leakes . Carburetors can vary and should be adjusted where they run best as said in post number two . If not running on the slow idle circuit the GAV setting will effect idle. If the GAV is set TOO rich and the carburetor isn't on the idle circuit it will lope .

[JoeCB]

Thanks guys. and the model basics link was very informative

Joe B