Leak down testing (not strictly EFI related)

[Johnny]

sam2 at ridgecrest.ca.us wrote:
> 
> >Typically, you would use 80psi on the supply side. In aviation, again
> >typically, when the cylinder gets down below 60psi, it won't pass. In
> 
> You mean you can't use 60psi? How do you hold the piston at top dead center
> at 80psi?

What I meant was, with the supply side guage reading 80psi, the other
gauge shouldn't read below 60psi, but your milage will vary. To keep it
at TDC, you get it centered really well first, and then hang on like
hell to the prop to keep it from starting to go one way or the other.
Usually, I rest the prop blade on my shoulder, or get someone to help
while I read the guage. In a car you put a breaker bar on the crank bolt
and brace it against the floor or the frame or whatever you can. The key
is to get the piston really centered on top first. Let the 0 angle of
the con rod help you out.

-j-