I call this scenario "The saga of my 37 Buick". Same problem that I was NOT going to let whip me. I knew it was fuel percolation as Jerry said because when it finally started it rolled out a big cloud of black smoke. First I re-routed the fuel line from pump to carb completely away from any heat source. Next I milled out a custom finned heat shield/heat dispenser that not only insulated but had a lot of surface area to dispel heat. I then put a ball valve at the float bowl inlet so I could cut the fuel off and let engine run to use up fuel in the bowl. Had a friend with a starter/generator shop build me a custom starter that had the case seam welded to cut down on fields pulling away from armature and 6 volt guts to really spin the engine. Opened hood after a long run to let heat out of engine bay (this helped) and even rigged up an old windshield defroster fan to blow across the carb while hood was open. Never cured the problem but come up with a band aid that lets it start; a real GM HEI distributor with plugs gapped at 0.060 for a hot fat spark. I guess I used a sledge hammer to kill an ant but it DOES start. Pic is of an Olds V8 dizzy modified to fit the straight 8 Buick which is like a 235 with two more cylinders.

http://s32.photobucket.com/user/coilover/media/Dar%20Dog%20HEI%20003_3.jpg.html

Evan