Originally Posted by
mberndt
I wouldn't go as far to say it is acceptable... Yes, it will show you when the piston is at the top of it's stroke, but it can potentially damage the piston, and it is supposed to be done WITHOUT a metal rod.
Besides, a flashlight and your eyeball can do the same job, so why not just "eye" it out?
you are not gonna damage a piston by putting a length of metal rod into the spark plug hole and turning the crank by hand till you reach TDC. It is extremely acceptable. If you damage a piston with a metal rod the size of a pencil, than your pistons are made out of paper.