Yup .040 in the hole flat tops I have already took apart to pairs of stock heads cc d them both came at 64cc both motors were 0.040 in the hole. One motor was a 90 and the other 89. Roller motors had taller pistons.
Thank you... indeed good to know. The early 318's were even higher. I put in 4 cc's for small eyebrows.... so yours have none? Gotta keep modest on the lift if no eyebrows.... which your reground cam does.
