[SlammedRanger]

Did you do gt thunder head studs? Get the head skimmed? And did you torque everything properly? Sounds like it blew a headgasket. Also did you stagger the rings properly? Do a proper break in procedure? Was the piston and cylinder checked for proper clearance by a competent engine machine shop? Sorry lots of questions. But lots of possibilities here.

 

[SlammedRanger]

Yes I got the GT thunder head studs. Sent the cylinder and piston to a local shop to be bored to match each other. I didnt have the head skimmed but never had any leaks from the gaskets do i just cleaned the surfaces real good before putting it back togethet. I got the rings on the piston properly and everything was torqued to spec. Was starting the break in process when this happened. Wasn't hammering the throttle or anything, just putting across the yard to make sure everything sounded and ran right.

When you pulled the head off originally did you untorque in steps or just remove each bolt all the way. You could have warped the head sligtly if you did the second option. That is why you get the head skimmed or run a virgin file across it to make sure its nice and flat. Or you will blow headgaskets. Odd thing is usually the gt thunder studs fix the warp anyway. Did you get a valve job done on it? Check valve guides?