I'm planning on doing a leakdown test and was wondering if it matters which spark plug hole is used (upper vs. lower).

Also, I know how to get TDC at Cyl. #1. How many turns are required for each successive cyl.? Memory tells me 240 degrees but wanted to make sure.

 

should not matter which spark plug hole.

 

120 degrees. 1-6-2, and then you're back TDC for #4 to then do 3 then 5.

(I suppose you could go 240 to do them 1-6, in order.)

 

Use the one that is easiest to get to.