The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - It’s cold outside. Carburetor choke on stock engines.

geezer#99 · 02-01-2014, 03:25 PM

A lot of manual choke carbs have a similar cam like yours that the idle screw rides on to give you a high idle. On your carb when the choke is wide open, the idle screw is sitting on the cam like in your old pic. When the choke is closed the idle screw rides up the cam to give you a high idle. Most factory set ups are made to give you a high idle with a further closed choke plate. Problem with that is that as the motor warms up you need more choke opening to keep it from running too rich, and you still need the rpm. Pushing the choke in opens the choke but also drops the rpm and your motor might like to stall.
I always preferred more rpm with less choke opening.
On your carb that's easily done by grinding on the cam at the point where the idle screw makes contact on the cam when your choke is fully open. You only need to remove about 1/16 to 1/8 inch. THen you screw the idle screw in to maintain your idle.
Your high idle will work like normal albeit a bit higher rpm.

02-01-2014, 03:25 PM	#36
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,522	Re: It’s cold outside. Carburetor choke on stock engines. A lot of manual choke carbs have a similar cam like yours that the idle screw rides on to give you a high idle. On your carb when the choke is wide open, the idle screw is sitting on the cam like in your old pic. When the choke is closed the idle screw rides up the cam to give you a high idle. Most factory set ups are made to give you a high idle with a further closed choke plate. Problem with that is that as the motor warms up you need more choke opening to keep it from running too rich, and you still need the rpm. Pushing the choke in opens the choke but also drops the rpm and your motor might like to stall. I always preferred more rpm with less choke opening. On your carb that's easily done by grinding on the cam at the point where the idle screw makes contact on the cam when your choke is fully open. You only need to remove about 1/16 to 1/8 inch. THen you screw the idle screw in to maintain your idle. Your high idle will work like normal albeit a bit higher rpm.