903 cylinder

i am rebuilding my engine, is 70 mm is the maximum overbore for the 903 block correct? i would like to install a 12.5:1 engine kit 1015 cc's

that is the maximum with stock sleeves.if you are splitting the cases id suggest finding a 1015 cylinder block and boring it to 1075 with 10.25:1 pistons.this way you can use these pistons in another motor easily the 1015 pistons are going to limit you to very thin 900 sleeves or a standard bore 1015.the extra cubes with the 1075 kit will gain you more horsepower plus you will not have as hard of a time finding fuel with the lower compression. goodluck,happy wrenching!

thanks for the help. now.... to find that 1015 cylinder. if anybody has one they would like to sell or trade for some z stuff or even car stuff... pm me. thanks

let me do some digging,where are you located? goodluck,happy wrenching!

bangshift440rt wrote:

now.... to find that 1015 cylinder. if anybody has one they would like to sell or trade for some z stuff or even car stuff... pm me. thanks

you want a 1015 cyl to bore? I have one that needs bored, 1075 will clean it up... $10 + postage.

also have a 1015 with pistons, not sure but look to be about 13 to 1 compression.
later! Bob

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i am also in pa, what area are you in?
+what brand are the pistons?

If your looking for a set of 1075 look up suicycle in Nampa Idaho. Last year they had a set of new Weisco 1075's for $300. They might still have them laying around.