The short version, does okay just driving around but my driveway is steep, and pretty long, and once the car starts up the driveway it starts stalling. If I fan the throttle it will pick up, usually I pop neutral and let off the gas and it stumbles but then will catch just long enough to get it to the garage. Once back flat, I can slowly get it to rev back up and then it does fine. Also, if I stab the throttle, let off, then stab it again, it will stumble and die, starts back up with a lot of pumping of the pedal but once it starts back up, does fine. Motor is a 406 stroker with a holley (not sure of the number), average fuel pressure is around 5.5 cruising around and doesnt fluxuate much, the pump is a holley blue. I bumped the pressure, it was running 3.5 when I got it and under any deep throttle it would seem to go dry about the 1-2 shift, pressure drop to 1-2 psi. Now pressure stays pretty constant after playing with regulator but still cant hammer down and run through the gears without bog stumble and sometimes stall. Any thoughts? I can get carb number, it looks like a 750, but Im hoping the incline symptom will help diagnose and that this problem may be generic to carbs and not holley specific. As always, any thoughts or advice is super appreciated.

 

Check the carb and see if it has a "whistle" in it. If not, you need to install one. If the carb does not have a "whistle," you will get fuel slosh at steep angles which will allow fuel to slosh out the vent tube and down the venturi, causing the problem you describe. We have the same problem on transverse-mounted Holleys on road race cars, which will pull enough lateral g-force to cause the same issue if a whistle is not installed.

The white vent extender is called a "whistle":







Lars

 

That sounds like fantastic advice, my immediate thoughts were either overflow from angle or a blocked vent sonehow due to angle causing fluid to amass in one part of the bowl. I am not familiar really with holley, I normally run edlebrock so I called my parts guy and he has the "whistles" waiting for me to pick up in the morning. Will that help the throtyle stab and die, or do you feel that may be a seperate issue?

 

the throttle stab and die issue could be the accelerator pump or the linkage that activates it. Need to know which Holley, list# is on forward face of airhorn.

 

Make sure the front float level is set as well.

Jebby