Carburetor And Black Smoke Info (Long)

Posted by Allan in NE on November 21, 2005 at 05:02:15 from (148.78.243.25):

Hi Guys,

This is kinda long, but I just wanted to pass this info on 'cause it was a new one on me and you guys may or may not already know 'bout this.

I thought sure that I was going to have to buy another one of these Marvel-Schebler carbs, as I have overhauled about every kind of carb known to mankind and this one really had some really weird symptoms.

It ran fine at idle and seemed "pretty good" at wide open throttle, but anything in between it would just absolutely "fog" black smoke. Wasn't flooding per se, just pulling too darned much fuel. Ran way too rich and just gassed something awfull. Just absolutely sooted up the plugs.

The local red shop had ran it thru the carb cleaner and put a kit in it and this is why I figured I needed to pitch it and buy another good one. It acted just like someone had drilled out the main jet too darned far.

On top of everything else, it did not have a high idle adjustment built into a shutoff solenoid like the book stated. It just has what looks to be a brass plug with a metering jet on the inward side. Above this "plug" is where the main pickup tube with a larger second jet lives.

Anyway, at the end of the day, this main metering tube (# 33 in the drawing, second picture) is threaded and has to be adjusted for height (and richness) by varying it's depth in the bore of the bowl. Screwing it in further (raising it's height in relation to fuel level) leans out the carb; turning it back out or lowering the tube in relation to the fuel level enrichens the carb at anything higher than an idle speed.

First time I've ever had to remove a plug and reach in and adjust a carb from the inside. It really had me goin' fer awhile there. But, by adjusting that tube height position in the bowl, it cleaned 'er right up and she runs like a new one now.

Maybe this will save someone else a headache someday. :>)

Allan

Follow Ups:

• Re: Carburetor And Black Smoke Info (Long) Ron in Nebr 06:59:35 11/21/05 (2)
  • Re: Carburetor And Black Smoke Info (Long) Allan in NE 07:23:16 11/21/05 (1)
    • Re: Carburetor gas in the air intake michael21 22:10:22 11/27/05 (0)
• Re: Carburetor And Black Smoke Info (Long) RustyFarmall 05:55:47 11/21/05 (2)
  • Re: Carburetor And Black Smoke Info (Long) Allan in NE 06:23:49 11/21/05 (1)
    • Re: Carburetor And Black Smoke Info (Long) RustyFarmall 06:56:06 11/21/05 (0)
• Re: Carburetor And Black Smoke Info (Long) El Toro 05:50:56 11/21/05 (2)
  • Re: Carburetor And Black Smoke Info (Long) Allan in NE 06:13:59 11/21/05 (1)
    • Re: Carburetor And Black Smoke Info (Long) El Toro 07:07:31 11/21/05 (0)

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