I rebuilt plenty of consumer engines that did big hours and either the noise from a cracked piston or the wrsit pin slogging out the pin bore gave the game up.
I do feel many of the boats were too heavy for the looper and we also had many twin rigs that should of had v4's.
The 2 cylinders ones on the other hand broke rods especially when over revved until both 2 and 3 had the upgraded rods and that fixed the problems.
I guess the piston was heavily built on the skirt to allow for the windows and the rod angle/side thrust which didnt help the weight with the small wrist pin....
That all history now...
So anyone checked their port timing after fitting long rods?