[Flathead Fever]

I was a smog mechanic for 30-years and a Mustang hot rodder. Tuning has to be done in a certain order. The first thing is to set the timing which you have done. 10 degrees is good; it's the factory amount on my original '66 Shelby. Next You need to set the idle mixture warm, just 1 1/2 turns out is a place to start just to get it started but then it needs to be fine-tuned. You need to turn each idle mixture screw "in" the same amount on both screws maybe a 1/8 of a turn at a time, until it just starts to affect the idle mixture, then back them out evenly just a little at a time until it smooths out. Once you have the idle mixture adjustments maybe turn them additional 1/8 of a turn "out" or all-around driving, because of weather changes the mixture can change a little bit day to day. Both screws need to be turned out "exactly" the same amount. Now if you changed the "idle rpm" after adjusting the air fuel fixture you might want to check mixture again.

You can also take a bottle of propane and just barely open it and pass it over the carb. if you have the mixture adjusted correctly it won't have any effect on the rpm but if it is to lean the idle will go up and if it's too rich the idle will go down.

The last idle adjustment is the choke. Once you have the idle mixture set then let the engine cool down. Wait until it's a cold day and then make the choke adjustments on the electric choke or manual cable

Then you can start playing with the jetting to really get the carb dialed in. There is a lot to a carb to really get it dialed in.