Marvel carb
 

What is the adjustment for low idle after rebuild?

Re: Marvel carb
 

idle speed is kind of a personal preference. On my Marvel I adjust the motor idle speed when the car is fully warmed up, spark advance at about 8-9 o'clock. I then adjust the idle mixture screw. On a Marvel you are adjusting the amount of gas for smoothest idle. This is opposite of a Zenith, which adjusts the air.
Hope this answered your question.

Re: Marvel carb
 

Renner's Corner has a "slide show" of information related to many carburetors. At least a couple of these are probably of interest to you. The slide show can be stopped for better reading/screen shot.

I could probably spend the better part of the morning reading all that is there.

See https://www.rennerscorner.com/slide-show--info.html

Check out the rest of their site including gaskets/oversize shafts etc. VERY helpful people. They've forgotten more about 4 cylinder engines than I'll ever know.

Joe K