<VV> Using compression gauge to locate TDC ?

[Charles Lee]

I just tried (again) to locate the correct TDC, and I used my
compression gauge (actually borrowed from AutoZone, no charge) to locate
TDC.
 
I noticed that compression spikes each time the rotor passes #1, hitting
about 50-60 lbs one time, and then 110-120 lbs the next time,
alternating between the readings.  (I removed the valve so it does not
hold the reading, as I watch the gauge)
 
I'm assuming that the low reading is the exhaust stroke, and the high
reading is compression ?
 
This is a method I had not heard before, and I'm wondering if it's valid
?
 
Seems logical, but I wanted to run it past you guys.
 
The engine does not start in either position, so there IS some other
problem, but I want to make sure I have the correct TDC before I start
poking around.
 
Thanks again,
Charlie
1967 Monza 110 PG coupe