I recently ran a post looking to duplicate a Jahns piston. So far I have struck out. Yesterday while looking at the damaged piston it occured to me that it could be used. The damage is in the oil ring groove in line with the wrist pin. I started filing on the damged area to clean up the groove and get rid of sharp edges. I can put an oil ring in there now and it turns nice and easy and there is nothing on the sides of the piston that will damage the cylinder walls. These are forged pistons so i'm not worried about cracks or breakage. Take a look I'm open for opinions.:TU: I realize part of the bottom of the groove is gone but I think the ring will be OK without support there.
My worry would be not so much the support not being there but more if the end of the retainer ring found its way there and could pop out or hang up. If you made sure the gap didn't go close to there it should be ok, the oil ring doesn't get the force of compression. As long as it doesn't rotate to there it would hold ok. It might be hard for someone to weld that without causing more damage but if you know a good welder you could ask anyway. Just my thoughts. Steve o No:
Is this a custom piston, or can you find another non-Jahn's piston with the same dimensions to replace your bad one?
I have added a picture of a piston for a big block stroker engine 489 to the original post. As you can see in the picture the ring groove goes right through the wrist pin relief. So either the oil ring doesn't turn or it makes no difference if the end of the ring crosses over that area. My biggest concern with my piston is its so thin in that area so without being attached all the way across it might be to weak causing it to bend upward and pinch the oil ring. I have thought about using my dremel and grinding that area down more. I probably won't use it but its tempting. I have thought about using a forged TRW +.020 with a 10 to 1 compression to match the rest but I think the TRW is somewhat heaviero No: I hate to buy a full set when I have 7 good pistons. I also don't think welding would be as option its to fine an area plus it I think it would damage the piston. Thanks for your in put. Bob H.
