fuel delivery issue

What carburator are you running?
I fought heat issues with my 750 vac secondary holley all summer.
It would only start starving for fuel when it idled more than 5 minuates in temps over 85 degrees. Tried everything 1" phenolic spacer, raised the heater hose support on the front of the engine up 4".
The motor was not running hot, about 1/2 way up on the gauge.

I put a 625 street demon on it with a plastic body, and braded lines, it helped alot but it still started acting up in 90 degree temps stuck in traffic for 5 miles.
Once I drive it for a mile or so it would clear up.

I am thiniking that I also have a vent issue, because I have never had this problem before on any Mopar and I have a bunch from 1956 to present day.

I have never seen heat issues like I have on this old truck in 30 years with playing with these small blocks.