(quoted from post at 16:26:57 09/15/19) Start with the idle mix screw about 1 1/2-2 turns off the seat.
The main screw about 2 turns off the seat.
But chances are adjusting the carb is not going to fix the miss.
Do some more diagnostics...
Be sure you have a blue hot spark at the plug end of each wire to ground. It should jump 1/4 inch minimum.
Try to find the miss by pulling one wire at a time. Check the firing order. Look the plugs over, even new they will tell a story. Oily black could be oil fouled, wet with gas is not firing for some reason, clean as new, not firing possibly too lean, a vacuum leak. Check the points gap, check the distributor shaft for side play. Any play and the points will do strange things, not stay set.
Run a compression test, look for a low cylinder. Could be valve problem, check the lash, look for broken spring. A pair of adjoining cylinders could be a head gasket.
Everything needs to be right with the engine for the carb to function properly. Many an innocent carb has been blamed for problems beyond it's means. Be sure to check everything listed before attempting to adjust the carb, save it for last.
The fuel needs to be clean. With the engine off, fuel valve open, pull the drain plug on the carb, catch the flow in a clean glass. It should have a full flow, not a slow trickle or drip or stop. Look at what was caught, if dirty, the same is in the carb. Water will appear cloudy.
Check the air cleaner. If it's an oil bath, there is a mesh filter inside the canister that needs periodic cleaning.
Once ready to adjust the carb, get the engine up to operating temp. Be sure the thermostat is in and working.
The engine needs to be at slow idle, in the 400-500 RPM range. Backing the idle mix screw out leans the mix, in richens it. The adjustment is very limited, you are adjusting air bleed, not fuel.
The main is a little more difficult. With the engine at idle, open the throttle suddenly, listen for the response. Start turning the main screw in 1/4 turn at a time, repeat the test until the engine falters. Then start backing the screw out, repeating the test until the engine takes sudden throttle from idle without hesitation. A single puff of black smoke it the goal. You may have to fine tune under real load, but that can only be done in the field.
