I have some of the remains of a GMC 228 engines that I have been salvaging parts from. Last week fellow 'Bolter TUTS59 needed a set of GMC rods. I took the pistons (which Craig didn't need) off the rods for easier shipping and noticed that one pistons had these marks around 60 degrees of the circumference of the skirt. Is this "knurling"?
Last edited by Bill Hanlon; 07/29/20252:56 PM.
'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.
Way back in the dark ages Perfect Circle sold a bench top machine called a "Nurlizer" for shops without a lathe so pistons could be expanded back to standard skirt clearance. Back in the days when engines got 2-3 ring jobs between rebores, it was standard practice to knurl the skirts to compensate for wear. Average life of rings was only 30-40K miles on some engines.
"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!
'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.
2 years agp I redid a 228 for my employer who wanted to keep as many of the original parts as possible. I encourged a rebore, but no. Took the ridge out and knurled the pistons. Probably going to work ok as he hasn't used it since.
just retired and finally making headway on my project truck. 1940 GMC AC152.
Someone my generation probably did that 60 or 70 years ago. Knurling pistons was very common back then and it worked very well on GMC Zollner pistons because they were so strong to begin with.
I have seen Knurled pistons on several engines I have torn down. Most were worn well beyond being used again. The cylinders were often "Egg" shaped and would require boring.
~ Craig 1958 Viking 4400 "The Book of Thor" Read the story in the DITY 1960 Chevrolet C10 "A Family Heirloom" Follow the story in the DITY Gallery '59 Apache 31, 327 V8 (0.030 over), Muncie M20 4 Speed, GM 10 Bolt Rear... long term project (30 years and counting)
If you don't like driving yourTruck, you won't drive yourTruck..| Living life in the SLOW lane
The knurled piston I posted the picture of is a Zollner piston.
'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.
I stood and looked over Jerry's shoulder a few years ago as he knurled one of the piston's skirts that I'm now running in my 261. That was neat to watch, actually. And we had to borrow a lathe and a knurler in a Mennonite neighbor's shop, working by coleman lantern light on a machine powered by a belt off a 6-71 Detroit power unit.
~ John
A kid raised on Hotwheels, Matchbox and Tonka cannot be reasonably expected to own only one vehicle as an adult.
1949 Chevrolet 3804 In the Legacy Gallery | In the Gallery Forum 1973 IH 1310 Dump 1963 Kaiser M38A1 2001 International/AmTran RE3000 "Skoolie" 2014 Ford E-350 4x4 (Quigley)
Two years ago I had a set of pistons knurled and the pattern came back with the Perfect Circle logo in the knurl. Knurl then file to fit. Years ago I did that to a Ford industrial V4 in a Saab. Ten years later another local wrench called me up to find out what I'd done to the engine. It needed a valve job, otherwise running strong after another hundred thousand miles.
1951 3800 1-ton "Earning its keep from the get-go" In the DITY Gallery 1962 261 (w/cam, Fenton headers, 2 carbs, MSD ign.), SM420 & Brown-Lipe 6231A 3spd aux. trans, stock axles & brakes. Owned since 1971.
