Well the old 48 has done it to me again, after spending a large part of the summer rebuilding universals all new gaskets and seals, new clutch,dist.carb,water pump,thermostat housing harmonic balancer, I thought I replace the head gasket adj and grind the valves and be done at last, well after looking at the top of the block there is a crack running from the vavle seat to the cylinder and atiny bit down the wall, I just don't know, the joy of old car's, it never gave any sing of trouble.