1974 D300 360 fresh rebuild will not start
Do yourself a favor. Forget all the 'O'clock" references that are thoroughly mixing you up.
Prove your balancer TDC mark is TDC on #1 or #6 whichever is easier.
Then put #1 piston to TDC on it's compression stroke.
Remove the Passenger side valvecover, and
Go find Split overlap on #6 valves, as best as you can. Both valves should be similarly open.
If they are, then your cam-timing is close enough to run. And close enough to make satisfactory Leakdown numbers, and should post far better Compression test results
If your Compression Tester is reading 60psi on all cylinders, leaking into the CC, and split overlap is where it's supposed to be,
then ;
#1 install new Schroeder valves in the tool, the correct ones recommended by the manufacturer, which are NOT THE SAME as car or bicycle Schroeder valves; and
#2, repeat the test, cranking as many revolutions with a fully charged battery achieving about 300rpm or more; as it takes to get two consecutive same-psi numbers. This could take between 5 and 12 cycles. The fewer the better, but do not stop until you get two consecutive same or very near to the same numbers.
If you have previously poured gas into the intake, then you will have to either let it evaporate, or pour oil into the cylinders to wash it out. If you have oiled the cylinders, you will have to crank the engine long enough to distribute it , and pump the excess out. And yes, it will make a huge mess. The rings have to seal to the cylinders, and also to the ringlands.
As long as the rings are the correct diameter, the correct thickness, and not installed upside down, then the gaps of new rings, are not gonna be a big deal.
Like others have said; if 60psi is truly all that you have,
and the pressure by LeakDown test, is ALL going into the CC,
and split over lap is anywhere close to being correct,
then you got big trouble.
I would be pulling that hummer apart to see where I goofed.
Adding air to #1 at TDC does not leak past valves, but does past rings. WHY!??!?
Are you talking full compressor psi, often regulated to 120 or more psi? The answer to that is easy. It only takes milliseconds for that pressure to blow all the oil into the pan. Then the air is free to go where ever it wants, as fast as it able to.
At TDC in a worn bore, the gaps are opened up by .0031416 per .001 increase in bore size. The wear up there is often .020 or more, so the gap is increased from say .027 at the bottom of the bore to .090 at the top. And that is a superhiway for pressure loss. This is complicated by the new rings not sealing to the worn ringlands. And by the very real possibility of the cylinders, at the top of the bore, not being even close to round anymore. So there are at least 3 places the air could be scooting on by the rings.
