question for the carburetor gurus
11-10-2017, 12:47 PM
#21
Had a 1976 L-82, 4-sp
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If the fuel is still pouring out when the engine shuts off then fuel pressure is causing this which is due to a stuck needle valve open as DR has explained.
Edit: And it only takes a speck of grit to cause this.
Edit: And it only takes a speck of grit to cause this.
Last edited by resdoggie; 11-10-2017 at 12:49 PM.
11-10-2017, 01:27 PM
#22
Drifting
Thread Starter
I'll take a closer look tonight, but I think the gas stops pouring out of the boosters when I shut down the engine.
Vacuum at idle is definitely 20"hg. Gauge is accurate.
Vacuum at idle is definitely 20"hg. Gauge is accurate.
11-11-2017, 01:31 PM
#25
It's doubtful you accidentally installed two power valve gaskets--what likely happened is the one gasket sheared in half when the power valve was tightened down. The paper gaskets commonly available these days tend to do that.
Here's a little tip for the Holley DIY'ers--when installing the power valve(s), apply some light oil to the power valve gaskets and let it soak in for a few minutes before tightening down the power valve. The oil will allow the surfaces to slide w/o shearing, plus it allows the gasket to compress a little better which reduces the likelihood of the gasket taking a set once in service, which allows the power valve to come loose. Yes, I see this VERY often.
Oh--the oil trick works great on paper float bowl screw gaskets as well.
Eric
Here's a little tip for the Holley DIY'ers--when installing the power valve(s), apply some light oil to the power valve gaskets and let it soak in for a few minutes before tightening down the power valve. The oil will allow the surfaces to slide w/o shearing, plus it allows the gasket to compress a little better which reduces the likelihood of the gasket taking a set once in service, which allows the power valve to come loose. Yes, I see this VERY often.
Oh--the oil trick works great on paper float bowl screw gaskets as well.
Eric
So I put the carb back together using the 6.5 PV's. Bolted it all up, started the car, idled REALLY BADLY and now I have raw gas POURING out of the venturi boosters on the primary side. Lowered the float level a bit with the engine off, restarted it and it's still pouring out. Took the primary bowl and the primary metering block off, removed the power valve to inspect and found that I installed 2 of the gaskets under the power valve. They are paper thin, but could this possibly cause fuel to pour out of the boosters? I can't imagine it, but....? Called it quits for the night and will go at it again tonight. I haven't tried adjusting the float level while the car runs.....only because it won't stay running with this condition. I'll crank the floats down a lot this time to see if the condition stops. Argggg.
11-12-2017, 07:17 PM
#26
Drifting
Thread Starter
Got it all back together, no more gas pouring out the boosters. That's the good news. The bad news: as soon as the choke butterfly starts to open, the car idles like poop. It gets worse and worse as the butterfly opens until it no longer wants to idle. Giving it pumps on the gas pedal will keep it alive, but it backfires through the carb. It's as if there is no primary side of the carb once it warms up. Idle circuit plugged?
Edit: OK, I think I found my problem: I removed the base plate and looked at the holes that feed fuel from the main body to the idle fuel holes below the base plate. The gasket I used is covering those transfer holes! Duh! The rebuild kit that I bought includes a variety of different base plate gaskets, I picked the wrong one. I located the right one for my carb and swapped it in. Will install the carb on the engine tomorrow night and hopefully this will solve the last of this carb problem! Wish me luck.....
Edit: OK, I think I found my problem: I removed the base plate and looked at the holes that feed fuel from the main body to the idle fuel holes below the base plate. The gasket I used is covering those transfer holes! Duh! The rebuild kit that I bought includes a variety of different base plate gaskets, I picked the wrong one. I located the right one for my carb and swapped it in. Will install the carb on the engine tomorrow night and hopefully this will solve the last of this carb problem! Wish me luck.....
Last edited by Tonio; 11-12-2017 at 09:56 PM.