Ok here goes. The motor is a .030 over '70 318. I suspect that the motor was rebuilt sometime in the 80s judging by all of the orange silicone. It didn't seem to burn much oil before we tore it down but we did not drive it much.

New Comp cam, timing chain and oil pump. Scuffed the cylinders with red scotch brite and called the short block good. We picked up some JY 714 closed chamber swirl port heads from a '91 pickup. These heads were the transition ones before the Magnum and have rocker shaft oiling. I had a valve job done along with the correct springs for the cam. Edelbrock performer with a 1405 600 cfm carb. Felpro head and intake manifold gaskets.

The motor has been assembled for about a month.

During the cam break in I had one son in the car and the other one holding a flashlight to look for problems. At about the 7 minute point the lookout saw something bubbling at the rear PS exhaust manifold. I knew that we had exhaust leaks so I gave him a socket to tighten the nut on the stud. I looked again and realized that it was something coming out of the valve cover. I only glued the cork gaskets to the underside of the valve cover. I looked around some more and realized that it was water and that some was coming from the front of the valve cover as well. This is the valve cover with the PCV. I then had my son shut the motor down and it was at the 10 minute point. I had an old Prestone funnel in the radiator neck and the water was more or less "boiling" and not really flowing like I would expect. When the engine was shut down it pretty much erupted out of the radiator.

The underside of the valve covers and and different points on the rockers show evidence of water. After sitting 4 hours, the dipstick looks like it is just the Brad Penn that we were running. No water. We still need to drain some out to see if there is water in the bottom of the pan. The dipstick level seems normal.

I rented a tool to pressurize the cooling system to about 14 pounds and it never really bled down much.

This is the transition head from LA to Magnum and I ran an LA Felpro head gasket. The motor had a Felpro in it before and the new gasket seemed to match the old one.

Pressurized coolant during an engine run usually means a head gasket or a crack in the head I would imagine.

Opinions?