Now, there are 3 and 5 cylinder engines that don't follow that exact pattern, but finding the overlap point and then turning the crankshaft one full turn is the way to find TDC on the compression stroke. The early GM 90 degree V6''s also had an odd-firing cylinder arrangement where there were no exact TDC matchups. I like turning the engine over for for valve adjustments by putting the transmission in high gear and rolling the vehicle forward gently.
I once rebuilt a Ford 3000 3 cylinder tractor engine with a bunch of gear-driven stuff in the valve train- - - -idler gears, accessory drives, etc. There were about six timing marks to align, idlers etc. I always check timing marks by turning the crankshaft two turns to see if the timing marks re-align. Nope- - - -didn't happen. A couple of marks would align, but not all of them. After several attempts at re-timing, I decided to keep turning the engine to see if the marks would ever line up. 96 turns later, it happened! The gears were set up in a "hunting' pattern like a gear-driven clock by including one idler gear with an odd number of teeth to prevent wear on the same teeth constantly meshing with each other!
Jerry
