[scottj]

Wilf,
It is a common practice, at least among circle track engine builders to put a thin layer of clear silicone around all the coolant passages on both the deck and the head. They also put it around the studs and under the washers, even on blind holes since the coolant could migrate across the deck from the passages to the studs. This used to be something the Sprint Car and Late Model engine builders would do on their aluminum motors since aluminum moves so much during warm up and cool down, but now they’re doing it on iron block/alum head motors too. Actually the only gasket they don’t use silicone on is the carb.
Scott