G surges when we try to idle
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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=52534
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Topic: G surges when we try to idle
Posted By: fwo
Subject: G surges when we try to idle
Date Posted: 23 Jun 2012 at 6:51pm
Just got her yesterday.
Our new G runs smooth and strong at full throttle and also runs well down to a little below half throttle. But the governor starts surging at about 1/3 throttle and slower.
If I sneak the throttle down very gradually I can sometimes get it down a little slower before the surging starts.
So far I have cleaned the carb. By that I mean that I blew compressed air through all the orifices. I also replaced the spark plug wires which were in very bad shape.
Both the carb cleaning and the better spark plug wires greatly unproved power at the top end but didn't help much with the low speed surging.
What should I try next? Thanks.
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Kindest regards,
F. W. Owen, Homerville, Ohio
http://www.HomerProduceAuction.com - http://www.HomerProduceAuction.com
http://userpages.bright.net/~fwo/ - Owenlea Holsteins
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Replies:
Posted By: CTuckerNWIL
Date Posted: 23 Jun 2012 at 6:58pm
The manual tells how to adjust the governor to eliminate surge.
The governor bumper spring adjusting screw
is provided to eliminate surge from governor.
It is usually not necessary to use this
screw - however, if the engine does surge
the screw should be turned in slowly until
surging is overcome. If the surge screw is
turned in too deeply, it will increase the
r.p.m at which governor action takes place.
This increase would be from low idle to a
maximum of 700 r.p.m.
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Posted By: Gerald J.
Date Posted: 23 Jun 2012 at 7:25pm
Surging at low speeds can be a hint of carburetor running lean on the idle circuit whether by adjustment or by crud I don't know about the G carburetor.
Surging like that is caused by the engine slowing more than the governor expects when the throttle is closed, so the governor opens the throttle which gets the high speed circuit in the carburetor working that's not lean and so the engine speeds up more than the governor is calibrated for so the control system oscillates.
Lean at idle can come from dirty idle passages or low gas level in the float bowl or a small intake manifold leak.
Gerald J.
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Posted By: fwo
Date Posted: 23 Jun 2012 at 10:28pm
Fixed...no more surging at the low end.
It was as Gerald J. had told us. It was surging because the idle screw setting was lean.
I had to turn it in five turns. Then I went in and out by quarter turns until I found a very nice sweet spot! The G now idles perfectly even in the last-most, slowest notch.
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Kindest regards,
F. W. Owen, Homerville, Ohio
http://www.HomerProduceAuction.com - http://www.HomerProduceAuction.com
http://userpages.bright.net/~fwo/ - Owenlea Holsteins
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