Engine requires 20 degrees of initial to idle well...
................... On the video it says based off a dial back timing light.....................Anyone ever see a faulty db timing light?
ABSOLUTELY Back in my parts store days, one service we did was to send customer test gear in to a repair facility. I've personally seen at least 4 different timing lights THAT WERE NOT ACCURATE
I don't know about "nowadays" as it's been awhile.
For me the tests are simple
1 Establish true TDC using a piston stop (for the dampener)
2 Degree the cam, and at least know "where it is"
3 Either degree the wheel, or at least mark the wheel at a couple of important points, like 20 and 40, so you have "ballbark" and or use timing tape
4 Confirm your light with a plain 'ol light. You can find em used at garage sales, Craigslist, or even new ones won't break the bank
5 With things like MSD aftermarket ignitions, delay boxes, ETC, and mating off--brand distributors and modules (My case, Mopar dist, GM module) You MUST check rotor phase.
THEN after the above SIMPLE steps, you can worry about carburetor, check the advance mechanism, distributor wear, valve adjustment, vacuum leaks, etc.