[a.c.ward]

couple of questions first off:

1. mechanical or electric fuel pump?
2. HEI distributor?
3. Fuel filter clean?
4. headers or manifolds
5. stock behind the seat fuel tank or moved?

1 & 4 if mechanical fuel pump and headers, sounds like vapor lock. fuel boiling from heat in fuel pump. try wrapping a wet towel around the fuel pump, securely in place with zip ties or safety/mechanics wire, then test drive.

5 if that does not do the trick, check the fuel lines for close ness to exhaust system. if too close to exhaust, same symptoms above. move fuel lines around/away from heat source, test drive.

2 some stock HEI distributors get heat soaked. ensure that the module to distributor module to distributor body in clean and coated with heat dispersing grease, available at most box auto parts stores for less than $2.

3 & 5 if the stock tank is still in place, the truck is over 40 years old. there is a sock on the bottom of the fuel pick up line. the become very brittle and clog very easy. if they disentrigrate, minute pieces can clog the fuel filter.

all of the above happened to me with a similar setup in my 69. 383, world products heads, lunati braket master 2, holeey street dominator, 850 carb, headers, etc.....

pretty much started with fuel symptoms first, fixed the fuel line, filter, sock, new fuel pump, newer headers. everything was good, but had a hard start issues when cold. discovered the HEI module was overheating by accident. old school mechanic friend and I were sitting around, shooting the breeze one after noon, bench racing, when I told about my issues, he suggested I try the module electronic grease. cured all of the starting and running issues from then on, till I decided to try out a big big block. still working on it...

good luck, keep us informed.

AC
still in Afghanistan