[Jac Mac]

Appears to be an exposed portion of guide or K-liner. Smokey Yunick used to advise treating all alloy heads with ? sodium silicate? in the water jackets for heat barrier reasons. Would this also help seal porosity like this ? I know there are several ceramic sealers out there that can be used. But the best results are obtained when the casting is clean & uncontaminated .Perhap's a pressure test of any head prior to use would be cheap insurance & save a lot of grief down the track.

I know there are several times I have asked myself the same 'silent' Q.

Jac Mac.