Jack up the back. Put the trans in neutral and turn the driveshaft by hand. Count how many turns it makes for one revolution of the tire. That will get you the gear ratio.
Go back to basics on the carb tune. Float levels need to be halfway, or just below halfway up the sight glasses. Verify the proper transition slot exposure; you'll have to look under the carb for that. Once those are set don't mess with the idle speed screws anymore. Adjust the 4 mixture screws to get the best reading with a vacuum gauge and best idle quality. If this stuff is good and it still won't idle/idles too low, add initial timing, and/or bypass air through the center of the carb(if equipped). Look to start in the area of 18-22 degrees initial but watch the total. Your distributor may need a curve adjustment to keep the total in the safe range. While it's idling I like to give the pump arm a little bump and see how the engine reacts to the little squirt of extra fuel. If RPM slows down, still rich. If it speeds up, it wants a little more fuel. Ideally the RPM shouldn't change much at all with just a small quick bump of the arm. Do it for the primary and secondary. If it's still out of whack, then you'll have to look at changing pieces like the IFR's and air bleeds.
Oh...do this stuff with the engine good and hot!
