Vapor lock

[Y-Blockhead]

Originally Posted by mshmodela

In my newbie opinion if corn base fuel sits in a hot carburetor (after a drive) the fuel may turn to vapor more easier than 100 gasoline. I think though with cool fuel from the cowl tank flowing in the the bowl that's not likely to happen... But once you turn the car off and let it sit... you might in theory experience this... Tests and experiments could likely proves this once and for all... I might take a carburetor with a small port-hole on the side of the bowl and a camera to really prove or disprove...

When I was new to my Model A I would shut off the fuel while I went into a store (or where ever) and when I went to restart it would back fire and run terrible until I let it set awhile.

When I started NOT shutting off the fuel it did not act up. I can only assume that with the fuel shut off the gas in the carb got hot. Leaving the fuel turned on may have had a cooling affect.

I can think of no other reason for this phenomenon.

So now I just leave the fuel turned on all the time except when parked overnight.

Originally Posted by Big hammer

because of the nitrogen enriched fuels today!

I have never heard of "nitrogen enriched fuels". What would be the purpose of that. N2 doesn't burn and is lighter than air so it would just evaporate.