[Raptor]

Fuel line is a better option than rope, the separate fibers have been known to get stuck in the valves and cause problems. Rotating the crank as steve mentioned is a good safety measure however if you do that in combination with the compressed air, you will need to lock the crank in position, the compressed air will rotate the assembly and put the piston away from the valve again. One last thing to mention, no matter what method you use on or off the car, take a dead blow and a drift and smack each retainer to break them loose. If you skip this step, you will have a very difficult time getting the retainer/spring to compress and the valve to remain.