Found this post from a guy in a Model A group having issues with his Idle.
Auther: George Beyers
Several days ago, I posted that I couldn’t get my ‘31 Roadster, with a newly restored carburetor, to idle slow enough. Thank you for all the positive comments offering advice. I read, and investigated, each and every one without satisfactory results.
As a last resort, I completely disassembled the carburetor, checked every part, cleaned all the internal passages and reassembled. TWO TIMES. The Idle was still too fast – 7 or 800 rpm.
I could manually press on the Throttle lever on the carburetor and get it to slow down. That told us it was a problem in the linkage somewhere.
My assistant and I considered different ways to lengthen the linkage at different locations – including bending, adding washers or any other method.
Yesterday my assistant compared the Original Throttle Control Rod to the Reproduction part that was on the car.
THAT’S THE PROBLEM! The spring loaded ends are different. The Cutout opening doesn’t go far enough towards the end. Not much, maybe 1/16”, but enough to change the idle speed. We restored the Original Part and installed it. The car idles perfect. I can count the cylinders firing.
It looks like a Dremel with a small grinding tool could be used to make the reproduction parts work.
