[TA76]

I have a new Jet Rebuilt 800CFM Quadrajet on my 455 (been sitting on a shelf for over a year waiting on the engine rebuild so I can't just return it). The gasket around the air horn is saturated with fuel after running for just a few minutes. It also seemed to be leaking around the accelerator pump. I ordered a rebuild kit, replaced the float, needle & seat, accelerator pump and air horn gasket. The accelerator pump no longer leaks but still getting quite a bit of fuel on the air horn gasket.

I then switched to an old Delco rebuilt unit I had that has never been ran, same issue... car runs but fuel is wet around the front of the air horn gasket. My fuel pump is a new stock GM until. Could the fuel pressure be too high (bad pump)?

[many birds]

I’m no expert...but I’d start by checking the float level.

[Formulas]

Float level, float condition, float touching something hanging up, needle seat rubber cracked / degraded, sometimes you can end up with debris inside inlets when carb changing,
If I suspect debris I will turn the engine over with the starter with carb top off float out needles out and flush the line, rag over carb ignition disabled


some people are reporting high fuel pressures with stock style replacement pumps

[steve25]

Take which ever carb is off the car now, flip it up side down and dry off the fuel inlet nut and blow with your mouth into the carb,

If you hear air rushing into the carb then when installed on a motor it will without fail flood out on you.

A carb up side down with the float in that position holding the needle closed should not let air in when you blow into it!!

[Cliff R]

There are at least half a dozen reasons the fuel level is too high. (Fuel present at the accl pump hole where it goes into the airhorn)

Start out by checking the fuel pressure. Those carbs can EASILY take 7-8 psi without any issues anyplace. Beyond about 11-12 psi you will need a different pump or a regulator. For those reading this the early carbs with the large float and short hinge pin can be problematic beyond about 6 psi with the larger fuel inlet seat in them. They actually gave the entire line a bad reputation for not liking, wanting or doing well with high fuel pressure which is pure BS. As with many things on the Internet old/outdated/inaccurate information on many topics continues to get regurgitated on the Boards, and Youtube, etc, even thought the last time I checked it was 2021.

Check the float level.

Get rid of the clip on the needle, if not installed correctly it will cause fuel control issues and it isn't needed anyhow.

Check the gasket surface under the fuel inlet seat for pitting, or any material left on it.

If you are using a brass float toss it out and get a closed cell nitryphyl float. I see LOTS of problems with current production brass floats, enough to write several pages on here, just trust me and don't use one.

I put up some info recently about the JET carbs I've had sent here, and the info applies to several other carbs currently being supplied for these engines from other vendors, might want to do a search and take a gander at some of that as well........Cliff

[TA76]

Thanks for the info guys, will give it a look.

[Greg Reid]

I replaced the airhorn on a carb that I rebuilt a couple of years ago. The original was damaged. Never could get the gasket to stay completely dry after swapping that airhorn.. I belt sanded the mating surfaces as much as I dared. It's sitting on a shelf to this day...the real shame is that it runs flawlessly.