Quote:
Originally Posted by twowheels
A smart ass might say when they need it  but you're likely at the outer limits at 120 hours. A piston rep once told me the issue is not so much the rings (you can always slap a new set of those in) but the piston skirt gradually collapsing.
The GG250s run about 185psi iirc, but the 300s will fool you with a super low reading because of the compression bleed hole (I recording 135psi on a new 300 and just about died before I knew this).
Some would say leak-down is a better measure of health, but at 7000 rpm, how much time is there for leakdown anyway? Besides that you miss the dynamic sealing action of the rings ... best to take compression numbers periodically and change the top-end gear when they start to slip. |
what year 300's have the compression bleed hole?