The Stovebolt Site Forums The Shop Area Engine Shop Carter YF 2100S Won't Idle

I just rebuilt my Carter 2100S. I can get it to run but only with the choke. I can't seem to get it to idle at a lower RPM without it dying. All orifices were thoroughly cleaned and blown out with compressed air - idle circuit, accelerator pump circuit etc. I tested the accelerator pump circuit after I assembled it by blowing compressed air into the main discharge with the top off and the pump moved up and down freely.

The rebuild kit contained check balls and a check weight. Does anyone know if the 2100S needs a check weight on top of the check ball in the main discharge circuit? Not sure if that's my problem. On another note, I can put my old Rochester on and it will run so I'm confident that there isn't a vacuum leak elsewhere. A local carburetor shop told me that they rarely see YFs with vacuum leaks at the throttle valve. Not sure if that's accurate but I suppose its open for discussion.

Any assistance is greatly appreciated to point me in the right direction of what to check. Thanks!
Mark

The Carter 2100s uses an encapsulated INTAKE ball that is located in the diaphragm housing (the mostly square housing in the bottom of the bowl that holds the diaphragm) and a square pointed brass needle DISCHARGE valve (NOT a ball) located new the top of the bowl casting. The square pointed brass needle should have been in the repair kit.

Jon.

Thanks Jon. This is a rebuild kit that I got a few years back but didn't need it until now. I'll double check for the square pointed brass needle. I originally put the check ball in with the weight on top. I'll try changing that to see if it works.

Pictures, if this helps any.

Thanks!

Thanks again. Idles nice now. So far, so good.

I am having a similar issue with a Carter YF 2100S It will not idle. I rebuilt it with a kit from Mikes Carb Parts
I am replacing a Rochecter on a 235 Chevy with the Carter. During the rebuilt I cleaned and replaced a check ball and weight. The kit contained angular brass needle but I did not use it. Did using the brass neelle solve your problem?

The Carter 2100s NEVER used the ball and weight; the 2100s ALWAYS used the pointed needle.

If the rebuilding kit contained a ball and weight, then it would be one of the "one size fits all" variety.

The earliest YF carbs DID use the ball and weight, but it was discontinued and replaced by the pointed needle by fall of 1953. The 2100s was released in November 1953.

The headmaster of the Carter carburetor school once told me folks kept losing the weight, and it was replaced by the pointed needle.

But the single piece (pointed needle) has less chance of sticking than the two piece (ball and weight), especially on the later castings that were machine for the pointed needle.

Jon