55 Series 62 Carter Carburetor Idle adjustment HELP

Started by mark55, November 26, 2022, 03:23:04 PM

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I have a rebuilt carb installed on my 331cid Airconditioned Series 62. I have not attempted adjusting anything on it since I received it from the Rebuilder.The engine starts easily & the choke blade functions properly on cold start & after about 5-6 minutes of warm up time (idling smoothly at approx. 1100-1175 rpm) the choke blade opens straight up as it should. When I snap the throttle to get the rpm to drop to a curb idle (I am assuming it would be coming off "Fast idle") but the rpm remains the same & I can't really say that I see any change in the fast idle cam movement.I believe the hidden throttle plate adjustment screw at the base of the carb on (drivers side) is out of adjustment & possibly needs to be backed off ?
Which may create a different idle issue.
Please note that this carburetor had a "New" design change for 1955 featuring a
"Air Bypass" adjustment screw on the base plate (passenger side) I have both the 1954 Shop manual & 1955 Supplement manual which is suppose to explain all the fine-tuning adjustments etc.(CONFUSING!!!)
Note:Yes the rpm remains at that 1150-1175 even with the fuel pedal linkage rod &
transmission throttle rod disconnected.
I do understand adjusting air/fuel mix screws at the base (front) of carburetor but this "Air Bypass" is something I have no experience with & I don't want to mess up the rebuilders preliminary adjustments. Any help would be appreciated.
Thank you Mark Infantino.  IMG_0652.jpg

Joe Jensen


I have included a picture, your picture, and I added an arrow to your fast idle cam on the carburetor.  What you will want to see is that cam rotate from where it was in the picture (cold, choke engaged) to choke open.  Can you send a picture of this cam plate when the coke is open?

I believe you may have an adjustment issue where the set screw for the coke fast idle needs to be screwed in some and your idle screw screwed out some.  Hard to say for sure without seeing more.

Good luck!


The first thing you need to do, is make sure the fast idle cam is coming off. That is the cam highlighted in the above photo. Then you can adjust the idle speed and then the idle mixture. To do this correctly, you should have a vacuum gauge. Good Luck
 Thanks Wayne   


Thanks to Joe J. & Wayne for your helpful responses. Upon a closer look at the "Fast Idle Cam" I do see that is functioning correctly & after some engine warm up time & snapping the throttle it does come off fast idle (Please see picture)
I did back off the "Throttle Plate" hidden adjustment screw 3/4 turn (bottom drivers side) that now has my curb Idle at approx 700 rpm in neutral.
I also increased the "Fast Idle Cam"adjustment screw 1 full turn & its running at approx. 1200 rpm during cold start warm up. (these adjustments will be fine for now).
Moving on to the Air/Fuel mixture. I understand adjusting the (2)  left/right adjustment screws on the (bottom front) using a vacuum gauge etc.
What i don't have any prior experience with is this "Idle Bypass Screw" (see picture)
Nornally on other carburetors after adjusting Air/Fuel mixture I would be adjusting the bottom throttle plate stop screw (drivers side bottom) to set my curb idle speed. *The one I have been referring to as the "Hidden Adjustment Screw*
Thanks Mark