Join Date: Mar 2005
Location: Tiny Pebble, AR
Do these cars have a Fuel Vapor Recovery System? I'm assuming they do as starting in the early 70s all the emissions sheet starting going in and killed horsepower, etc. I wouldn't think you actually have a gas cap that vents to atmosphere unless it's a safety thing. Must be a path for the pressure in the fuel system to vent pressure to a charcoal canister or similar. Check your FSM for the Emissions system.
Also with that carb conversion maybe the PO altered something related to the Emissions/Fuel system that's related to your problem.
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