I am running 3- 94 carbs stamped ford on carbs on my 56 Y block 312 with an aftermarket intake manifold. They run fine but now leak onto manifold. When I shut down I can see gas dripping out of center discharge tube in all 3 carb. throats. Hard starting also.
If they are not heat soaking, his fuel pump pressure (including after shut-down) may be too high. Tell him to reduce it to 5 lbs. or less. But I’m betting on heat-soak . . .
What Power Valve to Use on Tripples
2.5HG seems to work best for most.
Surging is usually an indicator of a lean-running condition. Check for vacuum leaks at the carb base, the intake manifold where it installs to the block (or the heads if not a flathead) and any vacuum-driven accessories and their hoses or pipes (even a leaking 1/4″ wiper motor or trans modulator hose/pipe can affect idle characteristics). Worn throttle shafts/bushings will do the same as well.
Check the needle for damage to the viton tip. The tip is easily damaged when any pressure is put on it.
Make sure there is a gasket under the seat.
Make sure the old gasket under the seat is completely removed..
Check float level.
Test the float for leaks.
Move the float up and down to make sure it isn’t rubbing or binding.
Look for dirt particles in the bottom of the float bowl. Dirt may be getting into the needle & seat from the fuel system.
Make sure the float isn’t rubbing on the float bowl gasket.
Check the power valve in the bottom of the float bowl. The needle should be up, not bent. Also make sure the gasket under the valve isn’t damaged, or stacked.
Is the fuel tank vented and is the vent clear, some have an extra tube going to the tank and some vent through the gas cap.
One or Both Idle Mixtures Screws Doesn’t Change Anything