Shemp
07-24-2023, 07:14 PM
I'm overhauling a 1967 Johnson Meteor 100 - probably the last one I'll ever do. This is on my vintage hardtop cruiser, and I wanted to keep it vintage.
I've probably had 50 or so of these engines apart over the decades, and one thing has always bothered me - and that's the wrist pin fit.
Most of the engines I've had apart have wrist pins that have been pounded to the point of losing surface hardness and becoming rutted in the center where the needles ride.
I have always assumed that the wrist pins are full floating once the engine is warmed up. But the wear on the used wrist pins I have seen clearly shows wear only on one side of the pin. The pins may have rotated at one point, but they became locked in the bores of the piston bosses. Many of the pins show minute amounts of metal transfer from the piston onto the pin.
I would like to avoid this from happening in the build I'm doing now. If course, all the parts are no longer available, and I'm using new old stock items where I can. It just seems like the "tight" side of the piston boss is too tight.
I realize that if the pin was allowed to spin / float too easily, it might force out the retainer clips. These engines use internal tab snap rings ( square cut hardened sheetmetal ) on the piston pin bosses, rather than wire circlips.
I'm thinking that I could use Spirolox in place of the original snap rings. I don't want to take chances, though, so I'm asking for feedback from others before further consideration.
In conclusion - how to keep the wrist pins rotating for even wear - and whether or not using different pin retainers is a dumb idea.
Thanks!
I've probably had 50 or so of these engines apart over the decades, and one thing has always bothered me - and that's the wrist pin fit.
Most of the engines I've had apart have wrist pins that have been pounded to the point of losing surface hardness and becoming rutted in the center where the needles ride.
I have always assumed that the wrist pins are full floating once the engine is warmed up. But the wear on the used wrist pins I have seen clearly shows wear only on one side of the pin. The pins may have rotated at one point, but they became locked in the bores of the piston bosses. Many of the pins show minute amounts of metal transfer from the piston onto the pin.
I would like to avoid this from happening in the build I'm doing now. If course, all the parts are no longer available, and I'm using new old stock items where I can. It just seems like the "tight" side of the piston boss is too tight.
I realize that if the pin was allowed to spin / float too easily, it might force out the retainer clips. These engines use internal tab snap rings ( square cut hardened sheetmetal ) on the piston pin bosses, rather than wire circlips.
I'm thinking that I could use Spirolox in place of the original snap rings. I don't want to take chances, though, so I'm asking for feedback from others before further consideration.
In conclusion - how to keep the wrist pins rotating for even wear - and whether or not using different pin retainers is a dumb idea.
Thanks!