Re: has anyone every sand blasted a carb?

Posted by Andy Martin on November 30, 2004 at 11:35:11 from (64.219.39.195):

In Reply to: Re: has anyone every sand blasted a carb? posted by Theman on November 30, 2004 at 10:58:37:

The accelerator pump is effected by the stream of air bubbles in the main fuel tube with the holes on both sides.

This air stream is introduced through the idle circuit air passages. The air bubbles through the perforated tube as the fuel is drawn into the engine.

When the throttle plate is opened, the idle circuit is shut off. Since the throttle plate has opened, manifold vacuum is admitted to the venturi and the pressure around the fuel tube falls quickly. This causes the air bubbles in the fuel tube to explode and force the gasoline in the tube into the venturi and the engine. This extra fuel compensates for the engine's need for additional fuel to accelerate. I call this an accelerator pump because that is the function it performs.

It was some pretty slick engineering in the '30's by IH engineers. No moving parts, but it is what makes an H or M respond to load changes like a hay baler stroking. Along with an excellent governer, the carburetor lets the tractor respond to every stroke of a baler.

Carburetors with the air circuit plugged are very difficult to tune. One way to check is to adjust the idle mixture screw. On a lot of tractors the mixture screw seems to have no effect. This is because the screw adjusts idle circuit air, in for rich and out for lean, and if the circuit is plugged, the screw has no or nearly no affect on the engine. There is an arc segment on the engine side of the throttle shaft which serves as the idle circuit valve. It must be installed correctly and all the air passages clean in order for the carburetor to perform as designed.

Although the IH carburetors have no mechanical accelerator pump, they do need the function and it is served by the air bleed into the main fuel stream.

Follow Ups:

Post a Followup Name: E-Mail: Subject: Comments: Optional Link URL: Link Title: Optional Image URL: Email Notification: If you check this box, email will be sent to you whenever someone replies to this message. Your email address must be entered above to receive notification. This notification will be cancelled automatically after 2 weeks.

TRACTOR PARTS	TRACTOR MANUALS

We sell tractor parts!  We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]