Construction and other equipment - Quick crash course in Carb adjustment

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Quick crash course in Carb adjustment

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Construction and other equipment
Forum Description: everything else with orange (or yellow) paint
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=35570
Printed Date: 26 Jun 2025 at 12:59am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: Quick crash course in Carb adjustment

Posted By: Freighttrain
Subject: Quick crash course in Carb adjustment
Date Posted: 15 Aug 2011 at 9:33pm

Give me a quick crash course on how to adjust a Marvel Schebler.Just took mine apart,cleaned,replaced the gaskets,Idle needle,Float needle and seat.How do I set the valve on the bottom?The idle is pretty easy.Turn till it sputters then back off a little till it runs good.Atleast that is how I was told.But the bottom one I don't know about.Gotta figure out how to fix the throttle screw.Some numb nuts screwed it in all the way and jammed it and the spring tight.The stop was missing and I made a new one out of a roll pin.Now the butter fly doesn't close all the way.

Replies:

Posted By: Jim Hancock
Date Posted: 17 Aug 2011 at 11:04am

Hi FT.

The bottom screw is the load screw. You adjust it with the throttle wide open from what I had been told a many moon ago. If I'm mistaken, I can be corrected, but I don't think that I'm wrong. The needle screw is for the gas mixture when a load hits the engine. Think of it as the high speed adjustment. Screw it in to bottom and back it out about 2 turns and go from there on wide open. Shouldn't be off much. HTH. Have a good week.