My car runs fine except for when I floor it. It does this at any rpm. At high rpm, it's not quite as bad as if I floored it at 2 grand. If I did that, my engine would probably just die. It's a 650cfm double pumper. I set the idle mixture screws so it idles good. Think I should raise the float a little? If so, should I raise the primary, the secondary, or raise it a little on both. It's on a single plane manifold and the engine has a huge cam.

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92 RS carb'd 350 5-speed

The first step in tuning a Holley is to set both the primary and secondary float levels. They should be adjusted so the fuel is just at the bottom of the sight plug or dribbling out slightly when at an idle; no more, no less.

Then, adjust your idle and jetting. The symptoms you describe are indicative of a very lean condition (typically). Unless you're seeing a cloud of black smoke behind you when this happens, it can be assumed to be lean. The next question is, does this happen only when you jam it down quickly, or even if you ease it up to WOT? If only the former, then you have an accelerator pump problem: You may need a different shooter, different cam, or perhaps even a larger pump. If just the latter (okay while you're flooring it, then lays down), you have a secondary circuit problem. If both, you may have both an accelerator pump problem and a secondary metering problem.

But, make sure the floats are at the right place before you do anything else. Out of the box, my Holley primary float was way down, but the secondary only needed 1/4 turn down to be right on. Until both are right, everything else is moot.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. 2-1/2" cat-back, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 CC system w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker 2055 headers, 3" Catco cat & 3" catback, restalled TC, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

It does this any time I floor it. Ease into it or not. It still does it. I checked the primary float today, it was just comming out the hole so I left it like that. I raised the secondary a little and my car runs better than ever. I can almost completely floor it but it still messes up every now and then. I'd rather not change the jets if I have too. It's a brand new carb.

RSS, does it crap out then pick back up after its done sputtering and all?

i have that problem i just described, i think i've tried eveything and have a similar setup like yours but a vacuum secondary 750.

im going to put in a faster acting accelorator pump cam soon and see it that helps.

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former 305 crossfire fuel injection
350 cubes
hooker headers
750 vac secondary
700r4 with shift kit
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"no man with a good car needs to be justified."