i did a comperssion test on my first rebuild (12a)
the numbers were 97-100-97
with only 200 miles on break-in with used housings and rotors. oem seals.
it was only cranking @ 120-130 Rpms. what do you think of these numbers? it was only on the rear housing as i did not have enough juice to test the front
how much does cranking effect the test as i know the rpm should be alot higher

 

The FSM has a chart that relates cranking speed to compression numbers. Accurate results require 4 things, engine at operating temp, throttle wide open, altitude compensation and a cranking speed of 250 rpm. Since the chart only goes down to 200 rpm, I'd say your numbers are pretty good.

 

trottle wide open huh? i guess it makes sense now i think about it

 

Yep, it does and many tester miss that seemingly minor step.