Has anyone heard of seats on Holley quads getting weakened so that they open at lower fuel pressures? I've got a buddy that is running a 4150 on a stang with pretty well built windsor under it, but it runs like the dam broke inside it. Black smoke, the whole nine. The carb was good on the last track car it was on, and the fuel pressure is regulated down to about 6PSI. It ain't the only one I heard about recently thats doing it either. First question in my head was are you running it on an FI pump and pressure? But they're not. They're aftermarket high-volume, but the pressure is down within reason as nearly as I can tell. (HOLLEY presets their carb-application pumps as high as 14PSI on some) Is it possible that a carb run at a lower pressure will become sensitive to opening at a reduced pressure so that the needle and seat will unseat before they should? Of course - the other thought I had was that both carbs got traded around for a good reason, but Don says NOPE! He got it from a dude going to F.I.
Nuts - and Don has my manual right now... I didn't think it had sight plugs. If you're telling me what I think you are, this could all be really simple to check out! The sight plugs should be on the bowl ***emblies, right? Front or sides?
Is gas coming out of the vent tubes on the top of the carb? I would check the float level just to make sure. However, it may be a bad power valve, or the wrong size power valve. This would be letting fuel in to the power circuit all the time, instead of just when it needs it.
another thing to look for is the air bleeds plugged up. there's 4 small holes right outside the squirters, about .080 in diameter. inside ones are idle bleed & outside ones are high speed. they get **** in them all the time. also check that power valve...mel
If the float leval is high and wont seam to adjust, you could have a bad float. Are you running a fuel filter. If not, your needle might be sticking becose of the **** floating around in there.
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