the k20 piston will be in the hole with F23 block? i was thinking that they might stick out too much ( the dome) for the F23 head.

 

http://www.honda-tech.com/zerothread?id=1232811
from that site they said the compression height for f23 piston is1.181. so they both are the same? they will fit?

 

if that is infact true then they will fit. Compression height is the distance from the centerline of the wrist pin to the top of the timing edge of the piston. The timing edge is the height the piston would be if it was a flat top (basically think of it as the height the piston would be if you put it on a belt sander and removed the dome to a level surface). Dome height is another thing and needs to be accounted for by clay checking the motor. Remember to do the clay test with a spark plug in to make sure there is ample spark plug to piston clearance. The actual distances that are safe to run depends on builder preferance. hth.

 

so the only way to find out if the piston dome is too high for the F23 head is to clay it? can i find out with numbers?

 

have to clay? cant calculate this?

 

yeah you should clay since you really don't know how well the type S piston "fits" the f23 head.