Originally Posted by
5crossyourlip
what is a good tolerance on the rod before it needs to be changed on the m21...i have about 1 1/2 gallons after break in and the temp never got over 240
The M21 rod should be changed every 2.5 gallons. They will not show much stretching, but will fatigue. It will probably break in the middle of the rod, not at the bushing.