Thread: I'm outta ideas... PLEASE HELP!!!

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"it has a brand new elec. pump"

Have you monitored the fuel pressure at the carb inlet? Those old carbs don't like any more than about 3 psi. The pump might be overpowering the needle and seat in the carb, leaking a little raw fuel into the motor that after a while, could overwhelm the motor and kill it. It might like the over-rich condition when cold, but when warmed up, not so much so. Tee off with your plumbing and run a fuel pressure line from the carb inlet to the cowl of the car, right in front of the windshield. Just mount it up there temporarily so you can see the actual pressure. Use a regulator in the line and drop fuel pressure to 3 psi or even 2 psi and see what happens. Don't cheap out with one of those fosdick poorly made regulators. Get a good one and mount it solidly in the driver's compartment.

More fuel pressure at the carb WILL NOT MAKE MORE HORSEPOWER. It will however, overpower the needle and seat and give you running/tuning nightmares such as you are experiencing here. The old stock stuff such as you have might like 2-3 psi. Most modern 4-bbls will operate best with 5 psi max.

All you have to remember is these 3 rules.
1. MORE PRESSURE WILL NOT MAKE MORE HORSEPOWER
2. MORE PRESSURE WILL NOT MAKE MORE HORSEPOWER
3. MORE PRESSURE WILL NOT MAKE MORE HORSEPOWER