I just checked my compression today and got 93-94 in the front and 95-96 in the back using the leading holes,,,,,,,,,

(I used the how to info from this page)

http://www.rotaryresurrection.com/ro...lder/comp.html

another member said use the trailing holes,,,,,,,,

https://www.rx7club.com/showthread.p...ssion+question

who is correct????

 

Both...It makes more sense to use the leading holes because of the orifice dimensions compared to the trailing holes in the rotor housings, and the leading holes are at "dead center" during the compression stroke, BUT...

The FSM instructs you to use the trailing, IIRC, and the limits published are readings at the trailing holes...Besides, the trailing holes are easier to get the gauge plumbing in, by just a bit...

It's a personal choice more than anything...

 

ok----thanks
brent

 

http://fc3spro.com/TECH/FAQ/compress.html

Mazda recommends using the trailing plug positions.
This is due to the fact that the engine loses a couple tenths (in bar or kg/cm^2) when the apex seal passes over the trailing spark plug hole first.


-Ted