Farm Equipment - CA Throttle response

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CA Throttle response

Printed From: Unofficial Allis
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=211811
Printed Date: 18 Sep 2026 at 6:58am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: CA Throttle response

Posted By: DSeries4
Subject: CA Throttle response
Date Posted: 27 Jul 2026 at 3:33pm

I've been on a throttle response kick lately. Here's another one:

I cannot get my CA to idle low. Just guessing it goes from maybe a bit over 800 rpm to dead, no gradual reduction in engine speed. Above 800 rpm, it works great. Carb was already been rebuilt and fires up super fast. I just want to get the idle down. However, there is a bit of slop in the throttle linkage if that makes a difference.

Any suggestions?

Thanks again!

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'49 G, '54 WD45, '55 CA, '56 WD45D, '57 WD45, '58 D14, '59 D14, '60 D14, '63 D15D, '66 D15II, '66 D21II, '67 D17IV, '67 D17IVD, '67 190XTD, '73 620, '76 185, '77 175, '84 8030, '85 6080

Replies:

Posted By: DrAllis
Date Posted: 27 Jul 2026 at 3:46pm

You've backed out the idle speed screw on the rear inside of the carb?? Push down on the head of that idle speed screw with your finger while idling and see if it does go to slow idle or not. If it does slow down, change your throttle rod length at the hand lever 1/4" making it pull back on the rod farther. If it doesn't slow down with the finger push, back out the screw until it is slow enough. Really nice place for a screwdriver !!

Posted By: Les Kerf
Date Posted: 27 Jul 2026 at 4:45pm

The instructions for a Zenith Series 161 state for preliminary adjustment to back off the idle speed screw to allow the throttle plate to close completely, then turn the screw in until it just makes contact, and turn it in an additional 1.5 turns. This just barely uncovers the idle port, and the idle mixture screw initial setting is to be 1.25 turns open.

I have found these settings to be pretty close if everything else is up to snuff.