i was just wondering if the screw on the very front of the carb was a fuel mixture screw, and if it is which way makes it leaner, in or out?

Hi!

The mixture screw is at the bottom of the carb and screwing it in makes it leaner.

Hello chevy 250-6,
The screw that you are talking about is the idle mixture screw, it is pretty much only for setting the proper mix at idle.

If you have a nice idle, but you are rich or lean off idle, then your problem will not be properly solved by adjusting the screw.

Dan