Thanks for checking when you get time. Please tell me if I am figuring the math correctly. The stock 153 piston sits down in the hole .050 with a 3.25 stroke. You swap in a 3.60 stroke 181 crank all other things being the same. 3.60-3.25=.350 increase in stroke. .350 divided by 2 (half of the stroke increase is at the top half at the bottom)gives a upward movement of the stock piston of .175. .175-.050 leaves the stock 153 piston sticking out of the hole .125. Just a tiny bit too much positive deck IMHO. So the next thing tried is a stock 250 piston. 3.6 -3.53=.070 half of which is .035. Do I understand this correctly? If I have the math correctly and if you can tell me where both the 250 and 307 pistons come from and take measurements I can tell where your 307 pistons will sit in my 250 block. Are the pistons oversize? I realize that this is old hat to a lot of people here but some of us (me) are trying to learn. Jay 6155
