How do I keep the engine from rotating in neutral
 

My engine is in the car, and I would like to keep it in neutral so I can rotate to get TDC for different cylinders. However, to do a leak down test, I would like to lock it while doing the reading. I'm not able to put back in gear (have gear link disconnected). How can I keep engine from rotating? Any way to jam the crank or alternator pulleys?

Leave the other 5 plugs in the engine, and it will not rotate if at TDC for leakdown. I've done it with engine out of car.

Exactly at TDC for each cylinder is the trick. A little off either way and it will go that direction.

like JW said.

100 psi with it at TDC and all is good. a little off, ,keep your hands away and the wrench off the pulley.dont ask.

That seems kind of risky, wouldn't it cause damage if it rotated backwards?

Buy or make a flywheel lock. You will have to remove the starter for this. I have used one for my 951.

Use shift coupler........
 

Install the shift coupler to the transmission rod and use it as leverage to shift the transmission in gear. Everything would be reverse in motion. First gear would be like shifting to reverse using the shift coupler. Use the coupler to put the gear in neutral. And so on........

Tony