The Stovebolt Site Forums The Shop Area Engine Shop 1955 Chevy 261 rod bolts/pal nuts

I’m reviewing a book I have an engine assembly for Stovebolt 6 cylinders. my 1955 Chevy had “pal nuts” or those sheet metal locking nuts on all the rod bolts. I assembled the engine with a book I have as mentioned, and the book never said to use the locking or pale nuts, just to torque the rod bolts to spec, 35-45 pounds, which I did. My question. Did I make a mistake here? I see the pal nuts are only listed up to 1954 engines and my late model 235 parts engine did not utilize these special locking nuts. Should I pull the pan back off and use these? Or is torqued to spec good enough for this 1955 engine?

Thank you,

With that said I did order a set of new pal nuts, as much as I really don’t want to drop the pan᠁. But the question still remains, are they required on all 235/261 engines? Just out of curiosity.

Palnuts make good decorations for the bottom of the oil pan, and do absolutely nothing to keep the nuts on the rod bolts tight. I've found dozens of them lying loose in oil pans. A properly torqued rod nut does not need any sort of locking device.
Jerry

Well that is lovely. I bet in a perfect world I would have replaced the rod bolts/nuts with something self locking᠁ I guess I’ll just use the old palnuts as they locked up tight, and move on. Next time I’ll do things differently.

Weren't Palnuts used to keep the oil slinger caps on? Went on after the rod cap nut?

Man, I sure hope so...᠁᠁᠁᠁᠁᠁᠁᠁(must have, cause that's how they came off and that's how they went back on a little over two years ago...mine are on a 216 though).

No, that would create a huge gap between the dipper and the rod cap and starve the rods for oil. It would also make the dippers hit the troughs in the oil pan.
Jerry

So the rod bolts just hold themselves pretty much when torqued correctly?

Mitch-506, that is correct.

Jerry, you are correct. (That reaching was a little too far I suppose).

Au contraire mon frere.
CHEVROLET TRUCK SHOP MANUAL 1948 to 1951 Models, Engine Assemly, page 6-37, Assemble Pistons And Connecting Rods To Engine, step 7.
"Install "pal" locking nuts with open side of nut toward end of bolt. Turn "pal" nut up finger tight and then 1/2 turn more."
The procedure is basically to install the rod caps with the correct number of shims, install the dippers, install the cap nuts, then install the "pal" nuts.
The real question is, are pal nuts really needed for full pressure 235s with insert bearing, and without dippers?

Palnuts are not needed AT ALL on any engine. The stretch of the bolt when the nut is torqued properly keeps the nut tight. A Palnut is just an unnecessary decoration if the nut is torqued, and it will not keep a loose nut from backing off further.
Jerry

How about when a good amount of babbit gets pounded out (normal wear), causing the rod cap to jackhammer the now slack nut/rod bolt which no longer provides bolt stretch to keep the nut on?
The automotive industry has been know to pinch every penny until they look like a train ran over them. I'm thinking that those twelve pal nuts were there for a reason.
Modern engines don't have pal nuts on them. Could it be that the Stovebolt rod bolts don't provide as much stretch as modern rod bolts and therefor where shown to need a more secure measure such as pal nuts?
(He asked politely.)

Good try but no seegar, Carl. The Babbit is in a groove in the rod and the cap, with steel surrounding it. I can remove the Babbit altogether and not have any effect at all on the bolt torque. In fact, I do that when I'm boring Babbit rods for insert bearings. A rosebud torch and an air hose removes the soft metal in a hurry.
Jerry

OK then, I want a refund for all of the money I payed to Chevrolet for all of the pal nuts they needlessly wasted in all of my engines.
BTW, and for the record, I did not install the pal nuts on my newly rebuilt full pressure '53 Powerglide 235 last year. I have found too many of them buried in the sludge in the bottom of many oil pans in the past.