Quote:
Originally Posted by nkaminar
John, Below from http://model-a.org/symptoms.html which is a good site for the Zenith carburetor. You are running too lean. If you cannot fix it they have a rebuilding service.
Mixture lean and over heating
Common Causes
- Float is set too low.
- Lower Casting Bowl Passage is restricted to Main Jet & Drain Plug.
- Compensator Jet Orifice contains dirt or rust, or is too small.
- Gasket at Main Jet is too thick or multiples are used, resulting in tip being too low.
- Main Jet Orifice contains dirt or rust, or is too small.
- Upper Casting Fuel Line Passage is restricted to Float Valve via Filter Strainer.
- Lower Casting Comp. Jet Passage is restricted to Cap Jet via Secondary Well.
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To add to your list, Throttle shaft/carb body worn and sucking air in. I find this most common on old carburetors. Oversize shafts and bushings are available.
I'm not sure what carburetor the instructions are for in post #1. As far as I know there is no "packing nut" on the GAV
