I have a WC that I put a rebuilt head on the on I took of was a 3 inch head the replacement was a 4 inch , that came off a WD I had that one done at a local shop with all new valves and guides , put it on and it blows out the front water manifold gasket so I removed the thermostate and tried it with the same results , So I guess the head has a crack or some thing else is wrong I thought of having the 3 inch rebuilt using the valves and springs from the 4 inch,.making sure the head is checked this time.If I am right they use the same valves but different rockers ( guess I ll get the 4 checked and see if my thoughts are right on it first). Any help will be apprieciatted. THANKS DON