1966 Plymouth Valiant /6 & Holley 1945 carb can only get to idle at 1250rpm. How to get a lower idle without dying?

RustyRatRod said
Anything's possible, but they normally have more room than that.

Do you know where it's located? Can't find it in the service manual. I know there's that bracket for the transmission to the block, but what about the rubber one?