The Stovebolt Site Forums The Shop Area Engine Shop Keeper nuts on piston cap bolts

As I remember from the tear down, in reinstalling the piston rod caps, the nuts are tightened to specs, then a "keeper" bolt, thin metal same size and shape as the regular nut, are tightened to "keep" the nut from ever backing off. I have either misplaced one or something; any one know where I could find them, or even what they are commonly called?

They're called "Palnuts" and the best place for 'em is the trash can. They're totally unnecessary- - - -and likely to work themselves loose and end up in the bottom of the oil pan. They're about as useless as the cotter pins and castle nuts used on the old International truck connecting rods. A properly-torqued rod nut just doesn't come loose, and one that's not torqued correctly can be safety wired, cotter-pinned, or double-nutted and it's still going to get loose and wreck the engine!
Jerry

Edit: If you think the rod nuts need a little help, just clean the threads thoroughly with a solvent like brake cleaner or lacquer thinner, and add a drop of blue LocTite before torquing the nut. It will have MUCH more holding power than a palnut, and if the stuff existed 60 years ago, that's probably what Chevy would have used.
Jerry

Thanks for the info, my mechanic friend also said forget them, properly torqued nuts would not come off. Thats two - thats good enough for me. Any ideas why they were added to the engine - they are original.

Back in the dark ages when engines were expected to last forever, or at least well past the warranty period, the designers added some pretty redundant parts. Nowadays, the same manufacturers figure how many engine failures they can get by with during warranty and still make a buck. Palnuts were just one of those efforts to add reliability, but it was discovered they really didn't add any degree of safety to the assembly. As far back as the 1950's, I can remember my father tossing them out on every engine he rebuilt.
Jerry

If you want some check your PM

One thing that makes the 216 different in regards to the rod nuts is that they do up against the soft sheet metal dippers, not a hard rod surface.