It is not a problem with porosity but a problem with the casting plugs put in by Offenhauser, which have a propensity to leak when using hot water heat. Some people JB weld them shut, I prefer a permanent solution as suggested/highly recommended by Tom Langdon and others.
see picture as it is worth a few words if not a 1000
Thus, the question for those who may know: Do they remove the original plugs or lay over an aluminum plug/slug over the top of the existing casting plug and weld it in place? If people have done both, any thoughts on which is better? If removed, how hard and what is used to remove?
I don't want to f-up the manifold well getting it ready for the welder.
