Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor

Time to finally dial in the circuits on this W72 carb...

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Cliff Ruggles:
If your e-choke conversion has one wire and grounds on the housing you MUST block the vacuum supply to the housing.  The two wire variety (rare) allow the gasket to be used and you can block the vacuum supply where the heat supply tube attaches to the housing instead.

Folks associate running lean with running hot, and leak with improved fuel economy. Two myths in this hobby that get regurgitated on nearly every Forum I've been on since the Internet was introduced.......

nUcLeArEnVoY:

--- Quote from: Cliff Ruggles on October 30, 2021, 12:20:49 PM ---If your e-choke conversion has one wire and grounds on the housing you MUST block the vacuum supply to the housing.  The two wire variety (rare) allow the gasket to be used and you can block the vacuum supply where the heat supply tube attaches to the housing instead.

Folks associate running lean with running hot, and leak with improved fuel economy. Two myths in this hobby that get regurgitated on nearly every Forum I've been on since the Internet was introduced.......

--- End quote ---

I'm using one of your e-chokes which grounds through the housing, and I don't use a gasket, obviously. But to maintain that bypass air, I have a vacuum tube routed from the choke housing to the little filter in the air cleaner that normally filters the air entering the hot air choke tube. I would think the metal on metal seal of the choke housing and e-choke is enough to prevent contaminated air from getting in, otherwise the air coming in through the vacuum tube is filtered by the modulator in the air cleaner just like from the factory, only it's no longer getting heated. Like I said, doesn't make any difference in the e-choke operation. It works just fine, only now I get to keep the original bypass air design.

So talking rods, what secondary and primary metering rods would you recommend I get, given what's been done to the engine and the carb unit #?

Cliff Ruggles:
"I would think the metal on metal seal of the choke housing and e-choke is enough to prevent contaminated air from getting in"

It does NOT establish a positive seal so would suck unfiltered air into your engine.  Block the vacuum before the housing.  It may not even miss the lost bypass air and if it did you can simply open up the bypass air holes in the baseplate slightly to bring it right back.

If you want to try different jets and metering rods call the shop.  I have full tapered 45C metering rods that would provide a much wider range of control with the APT that a "K" metering rod.  They taper from .045" all the way to .026"........

quadrajam:
Newbie 1 finger typer here...
Back to the lean/hot thing. Hot only happens at very high
cylinder pressures like WOT. You can lean it out all you want
at idle or cruise and it will just shut off.

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