hi guys i just picked up a 68 c10 lwb 396/air truck but its only a custom while trying to tune the carb i bought a fuel pressure gauge (marshall liquid filled) i noticed buy accident when truck runs for 15 plus minutes it loses fuel pressure. it had a clear filter before the carb next to the head , and when it gets warm it stats pumping bubbles and filter has no fuel but truck still runs! yesturday i replaced the holley 80gph pump with a new edelbrock 110gph changed the feed line to carb from pump to alum and wrapped it with heat barrier tape, moved filter under truck between cab and frame lines filled tank in truck and same problem. i also bought a laser thermometer when i was out to try to carify the problem, it showed after 10 minutes of running (idle)header tubes near heads were 480-500 deg collecters were 400deg, and frame rail fuel line is on from inner fender read 140deg and thermostat housing was only at 130deg.
i removed headers and am painting them with cermic header paint and ordered dei titanium heat wrap for them and also a therm sleave for the fuel line i noticed a 200deg reduction in exhaust tubing 1" past collecter with the bull **** cermic paint so i figured its worth a try.
sorry for all my rambling i appoligize the trucks motor is a 72 402 thb code 210hp, has i think hedman headers, 241 heads, comp solid lifter cam large but dont know specs(280) range truck dosent idle nice, comp springs, pushrods, roller rockers. old edelbrock? ( id ground) mid rise holley 3310 flamethrower 2 dist and coil.
i guess im wondering is there anythink else im overlooking. dose this sound like tippicle vapor lock issue? heres some pics
