Quote:
Originally Posted by Benson
There are 3 adjustment screws normally on a stock Model A Zenith.
1. IAS Idle Air Screw on upper casting (45 degree angle) for adjusting Idle mixture.
2. GAV Gas Adjustment Valve lower casting (45 degree angle) on the same shaft as the choke lever.
3. The idle speed adjustment screw on throttle shaft
Then there is a fourth possibility.
4. A "T" handle on bottom coming out of the normal drain plug. (90 degrees to the casting)
This is not stock and if it is there it is the cause of this problem.
Which one are you turning 4 1/2 turns?
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No T handle, and it is the GAV that I am adjusting. It is not 4 1/2 turns totally. Following the Zenith Adjustment that I uploaded in Post 1 I ended up
with the GAV 2 1/2 turns open. It idles and runs up to 50/55 MPH at 2 1/2 turns Open ,but will start and idle at 1/4 turn open. will backfire through the carb if exhilarated. Turn the GAV 1 to 1 1/2 turn it will run up to 35 MPH, Turn it another 1/2 turn it will exhilarate to 45 MPH. finally to 2 1/2 Turns open it will exhilarate easily to 50 MPH then slowly climb to 55 MPH. BTW No vacuum leaks.