fresh carb rebuild and airhorn gasket seeping gas

[shadetree55]

Carb # 17059206 rebuilt a couple months ago for my 55 Chevy restoration. Stock 307 built for driver.  It first started fine but last couple times harder to start and now the air horn gasket is seeping gas. I've built many of these over the years and have never had that happen. New nitrophyl float and metering well plug kit installed an\nd epoxied.  Even with the seep the carb  performs fine. Just don't need a fuel leak on a fresh finished 55. Any advise would be appreciated.

[Kenth]

Crap between inlet needle and seat?
Inlet needle clip mounted in one of the holes on float arm?
Too high float setting?
Too high fuel pressure?

[shadetree55]

Thanks, I know the needle isn't in one of the holes for sure and new fuel tank, inline filter before pump and paper filter in carb. After reading several people's posts on several forums I'm leaning to maybe a combo of both, float too high and lots are complaining about aftermarket pumps (I'm running a Precision" from O'reillys ) the pressures are too high. I ordered a Delphi from rock auto that supposedly is a 5-7 lb pump. When it comes in I'll pull the air horn, recheck new float, install new needle and seat and horn gasket and see what happens.

[Kenth]

Only filter recommended before pump is the nylon sock in tank.
An inline filter ahead of the pump will restrict fuel flow from tank.

[lightning boy]

Like Kenth said, don't install a filter before the pump. the inlet pressure to the pump will drop too low and cause all kinds of problems. It's called NPSH, there have been volumes of professional papers written on the subject.

[shadetree55]

I get that but what would low pressure have to do with gas seeping around the air horn gasket??

[quadrajam]

Might be a good time to set up a pressure gage on fuel line and monitor it.
Then you'd know which way to go. Make sure to watch it for a few minutes
after a hot shutdown also.

QJ

[Cliff Ruggles]

Did you get your rebuild kit from me?

I stock .015" thicker main body to airhorn gaskets which help sealing up carbs that seep at the front between the center screw and long hold down bolts.....

[shadetree55]

no I didn't. At the time I didn't know about your kit. I did readjust the float to .375 and at the same time installed a new Delphi pump because I thought maybe the precision pump might be too much pressure. Evidently not because I installed the delphi pump which was "supposed' to be a 5-7 psi pump. Evidently it wasn't because my carb flooded like crazy with it. Removed it and reinstalled the precision and all seems to be well now. If it acts up again I'm just gonna yank it and send it to you. Tired of fooling with it.

[Cliff Ruggles]

Before you do all that put one of my rebuild kits in it and the .015" thicker main body to airhorn gasket......