Running out of fuel at 40-45 mph.

[geezer#99]

Originally Posted by 1970pelle

Fuel pump is in stock location, lower right front corner of the block. Has 3 lines, 3/8 line is fuel supply, 5/16 line is return to fuel tank, 1/4 line is a vent line.

I do not have a blocked vent line. I do have a vent line run and its mounted to the side of the core support and runs to the top of the support. There is a space in the support near the radiator that you can hide a hose in. I have the open end of the vent higher than the fuel tanks.

I don't have a air filter blockage, I'm using a 14X4 K&N air filter with a K&N filter top. So there is no lack of air supply.

No I'm not running a spacer between the carb and intake. I thought about it, but with the air gap intake manifold didn't feel I needed one. But willing to give one a try, I have the clearance for one.

I have breather's in both valve covers

I'm using a HEI distributor, with a adjustable vacuum advance. I have to go check my notes on how I set the timing.

Engine vacuum at idle setting still 15. Running down the road at 40-45 with my foot out of it almost 20. Now remember I'm at sea level in some places below. So I usually have more vacuum than needed.

I keep my stuff clean & neat. I have done everything asked, but it doesn't hurt to check again.

Air gap keeps the fuel vapor cooler. Heat still transfers thru the intake into the carb. Spacer will help.
And a regulator will help.

When it craps out, do you look and listen inside the carb to see what's happening?
Any flooding, leaking, boiling noises?