Yeah I was going to mention the piston to valve stuff also. I'd pull the head off and clay check it if you didn't originally. I know of a couple of people who tapped valves with that same setup and the head wasn't milled.
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Don't bother giving me "rep", I won't return it and I think it is stupid.
Gracie Barra Clearwater
Gyms in Clearwater, St. Pete and Port Richey
pm me if you are interested in trying a free class at any of the gyms.