Yes Air would come out of the spark plug hole on the exhaust stroke, cause there is no plug to stop it from comming, on the exhaust stroke is when your exhaust valve which in most cases is your biggest valve will open to let the already spent fuel out of the cylinder . On a Otto cycle engine such as the one in your jeep, it has 4 strokes. 1) Intake 2) Compression 3) ignition 4) exhaust
It sounds like you caught the #1 on the exhaust. I would take dirty comanches advice.
I'm not too sure about Automotive engines, but On piston powered Aircraft there is a marking on the flywheel, that is splined to the crankshaft and a marking on the Crankcase itself, indicating TDC. Possibly there is such a marking on the jeep but yet again I don't service automotive engines. Automotive engines in comparison to Aircraft piston powered engines are much more complicated. A small example would be In a Automobile the engines are liquid cooled, aircraft are AIR cooled, by use of baffles and RAM air.