I am putting 307 pistons in my 250. they already have valve reliefs but I think they are not in the correct location. No matter to me as I am not needing them as I don't have a high lift cam. I foud a used set of pistons from a marine 307 engine on ebay and they were in pretty good shape. One didn't make it in shipment and another one I ruined trying to get the rods off. So I had 6 good ones left and got the rods off all of them without any damage to the pistons. Original GM so they had a compression height about .020 taller than any new ones you buy so I was happy. Also no chafer around the edge like a lot of new ones have. had the block decked only 20 to give me a little pop out of the pistons. I figure they will come out of block about .005

Last edited by Vman; 12/05/12 07:36 AM.