Inliners International Forums General Discussion Hi Performance Custom Sissel 12 port head intake manifold 194-292 in progress

Yes, piston to wall clearence.

The machine shop usually lashes 0.003 or 0.004 for street use. Beyond that, for tracks, the lashing should be more due to the heating, piston material or whatever.
If you lash a 4" piston in 0.012, the cylinder bores will be too big and then the wall to thin. Sometimes you can be lucky and nothing is going to happen, sometimes not.