Trick for finding TDC
 

Here is a trick that can be used to find the TDC of the compression stroke without a gauge. So I am working on a 3.4 swap and after doing a valve adjustment and timing belt change and it wouldn't start, I had to rule out my timing. I didn't have a vacuum/compression gauge to find TDC but I did have a condom and a piece of 5/8th inch hose.

I wanted to see if my timing marks liked up on the compression TDC so I taped the condom around the hose, "sharpened" the other end, jammed it into the #1 spark plug hole and gave it a twist. I then turned the crank and waited for the condom to get a hard on which would tell me the compression stroke.

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When I found the compression stroke, I then inserted a telescopic magnet into the plug hole and rotated the crank until it was at the top of the compression stroke JUST before it went down (exhaust stroke).
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My timing marks lined up at the cams and crank 0 mark. My problem is not my timing......must be electrical.

In place of the telescopic magnet, I recommend a plastic straw or a wooden chopstick. You started very close and were very careful, and the magnet is not TOO strong. But if one used, for instance, a long screwdriver, a mere slip of the wrist can gouge the top of the piston or screw-up the plug threads. The chopstick or plastic straw would just fold up.

Hell that's way easier, I always used a long hose stuffed in my ear to listen for compression.

One thing though, "just before the piston goes down" isn't the exhaust stroke, that'd be your power stroke ;)