[Michael C Henry]

With mine the more spark timing advance I ran the less carb idle screw I needed to maintain idle rpm. Or if I turned up the distributor spark timing advance up the engine idled faster so I'd have to back the idle screw out to bring idle down to a reasonable idle RPM.
Back in the day when points were the way , I could connect a test spark plug to #1 spark plug wire and ground it so the spark jumping could be seen. I could turn the crank and set the timing marks on about 14° BTDC while #1 was on compression stroke with both valves closed and then rotate the distributor untill the test plug in #1 wire sparked and then snug up the distributor clamp and it would end up being about 8° BTDC. IT DIDN'T WORK with modern pointless ignition. I was way too late After TDC.