How do you stop vapor lock?

[ajohn]

My 30 A is highly modified with header, Thomas head, inserted, pressurized rods and mains, synchromesh trans, 4 wheel disc brakes, weber 2 barrel downdraft carb. It vapor locks big time on a hot day in traffic, It had an electric fuel pump that it appears to do better without with a rubber gas hose from the firewall fuel filter to carb. I have been advised to buy aviation gas. Any thoughts or suggestions? Ajohn