<VV> Vapor lock?

[Joel McGregor]

Working on a '66 that will run fine as long as you don't let it hot soak for 10-15 minutes.  Fuel lines aren't touching anything, I removed an inline filter from the line forward of the engine compartment and all shrouds and hoses are in place except for the thermostat housings.  Engine doesn't seem to run hot.  (37K 110 on pump gas with almost no pinging)
If you run it down the highway for 10 miles and stop for 10 minutes it will start right up and run until the carbs go dry.  If I dump cold water on the pump and fill the carbs it will usually start working again and run fine until it hot soaks for 10-15 minutes again.  '64 95hp running the same gas has no issues.  I guess EMs are just better than LMs?  Stops for a shorter amount of time are usually ok.

Help!
Joel McGregor