I'm wondering if anyone has seen this. When I removed the head on my 216, each piston was stamped with the associated cylinder number, 1 through 6. There was also an "M" stamped on top of each piston. Was this maybe from a rebuilder stamping the number to use to reinstall the same piston in the cylinder it came from?
Since this is a direct "engine" question, I have moved it to the Engine Shop forum for further conversation and answers from fellow Bolters.
Good luck in your search for an answer!
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
Seems like a Sharpie would have been an easier and better choice to mark pistons than putting them in a vise or something and then punching a number.
I'd suspect they were made that way but what do I know?
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
Sharpies didn't exist when those pistons were stamped, most likely. If I was going to do something like that, I'd do it before I removed them from the engine. No idea why there's an "M", but the piston/rod assembly has to go back onto the correct connecting rod journal to keep the bearing fit correct, so numbering them is a really good idea.. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Pistons in GMC sixes from the 40s and 50s came with two numbers stamped on the top. 1 thru 6 for the cylinder number they were installed in at the factory and another single digit for the actual piston size. Below is the size chart for 270 and 302 engines.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
Anal retentive rebuilder probably did that. It's important on some engines to make sure that the connecting rod is installed the correct way. I wonder if he stamped the connecting rods to make sure that they were installed to match the stampings on the pistons.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
