You are exactly right George, in fact some racing engines like the Nissan GTP car are set at zero clearance at room temperature. Without pre-heating the motor and the oil, it won't even turn over. Mike --- George Roffe <geo3@earthlink.net> wrote: > My guess is because the E15/16 and GA16 have a cast > iron block. The cast > iron block will expand less than the all aluminum > SR20 block.