Did not totally understand the question, but the timing mark on the crank always tells you whether the #1 piston is up or not.

That is always correct.

But what you can not tell from the crank alone, is whether or not #1 is up for the firing stroke or exhaust stroke?

Only the cam tells you that.

If you take the cam cover off, you will see whether the valves are both up on #1, and it is ready to fire, or whether the exhaust valve is open and it is ready for exhaust.

Simple answer-4 stroke engine: Intake, compression, power and exhaust. Intake and power, piston traveling down. Compression and exhaust, piston traveling up. Yes, #1 piston will be at TDC when timing marks are aligned, but on either compression or exhaust stroke.

You.are write buddy but visit the near local dealer they helps you much better way

HI, Yes every time the crank reaches 0* or TDC the piston is UP.. What tells you if its compression or exhaust is the cam timing. Because the cam operates the valves.

hope this helps

good luck

tim

Have a dumb question. The crankshaft turns twice to one turn of the camshaft. When the timing mark on the crank is up to where it is aligned with the camshaft timing mark (6 oclock cam and 12 oclock crank) and when the camshaft mark is 180 (12 oclock cam and 12 oclock crank). Is the crank always at TDC cyl #1 when the timing is ar 12 oclock? 4 cylinder OHV GM 2.2L