VAPORLOCK

Are you positive is vaporlock? Have you checked to make sure near the tank that the exhaust isnt close to the fuel line?
Another thing you might check is any filters. Over time junk gets in the tank (or rust) and forms a fine grit that will clog a filter/strainer when stired up.

If you suspect vapor lock try this. Remove the fuel line from the carb. Go to home depot or lowes and pick up some clear tubbing and a barbed double sided fitting. Install the clear line to the carb and watch. You should see air traveling through the line. Keep in mind the tube is not technically rated for fuels so keep an eye on it. Fuels today even with high ethanol still have a higher "flash " point for lack of better words and a higher quality. Vapor lock is still a think but we have found that the ethanol in todays fuels in most markets degrades the rubber fuel line from the inside out. They have a tendency to collapse on themselves under a vacuum and simply pinch off your fuel supply. Just a few things we have come across on the vapor lock issue on older cars, and generators etc.... Hope you find your issue..

Forgot to add that if you install a 12v pusher pump as close to the tank as possible and replace your rubber lines if they are older we typically eliminate fuel delivery issues. Pushing fuel is preferable to sucking fuel.... We buy the napa brand pumps for around 50 bucks..

I got a used walbro and added the biggest fuel filter I could find to act as a reservoir. My 66 runs outta gas at 1/3 tank because theres not enough fuel pressure from the outlet not being at the lowest point on the tank.

shem