So I tore down an old 360 and had it machined 0.030 over, crank 10/10 , new camshaft and lifters, new springs, heads done completely.

Got it running for about 20 minutes to break it in and seemed to be running well. Fast forward to starting it up again a week later, and I see there is coolant in the oil. No visible leaks, spark plugs look fine. Just coolant in the oil, and fresh coolant on the valve springs and rockers.

I end up pulling the intake manifold and reseat it with valley pan and fresh RTV. All good? Nope.

Next day I'm prepping to restart it, and I see that there is coolant on the oil pan, starter, coming from the passenger side head on the corner.

I assume its the head gasket, so I loosed the head bolts and retorque them all 35-65-95-110 ft lbs. Should be good?

I run the engine briefly, and I can see the coolant start to drip strongly on the ground. Cut it off quick. Looks like half way down the passenger side head to the back corner of the head, under the head gasket is leaking coolant.

So where I am now, engine refresh with all new seals, leaking coolant on the middle to back of the passenger side head gasket. What could cause this so quickly? Why would it leak more after retorqueing the head bolts? I thought that would help.

Any suggestions welcome, Thanks in advance.

Shawn