I had thought about piston knurling (lower case "k" - no trademark)just last week. I had an engine with high mileage and lots of piston-to-wall clearance. I opted for new pistons to get away from dismal seventies-era low compression. I wondered why I hadn't heard anyone mention piston knurling in a long time, but thinking now it's probably because we expect an overhaul to run another 75 or 100,000 miles. When I was younger we didn't even expect the original engine to make it to 75,000.
ISTR knurling valve guide ODs as a way of squeezing a couple of tenths of a thou in the ID, to get the valve stems tightened up enough to last to the next rebuild. Granted, this was British Leyland, so the next rebuild probably wasn't that far off.
Ooops, link!
ReplyDeletehttps://www.enginebuildermag.com/2017/09/lost-art-knurling-pistons-takes-skill-guts/
I had thought about piston knurling (lower case "k" - no trademark)just last week. I had an engine with high mileage and lots of piston-to-wall clearance. I opted for new pistons to get away from dismal seventies-era low compression.
ReplyDeleteI wondered why I hadn't heard anyone mention piston knurling in a long time, but thinking now it's probably because we expect an overhaul to run another 75 or 100,000 miles. When I was younger we didn't even expect the original engine to make it to 75,000.
Thanks João!
ReplyDeleteISTR knurling valve guide ODs as a way of squeezing a couple of tenths of a thou in the ID, to get the valve stems tightened up enough to last to the next rebuild. Granted, this was British Leyland, so the next rebuild probably wasn't that far off.
ReplyDeleterdguy