wonder how this happened

you, upon investigation i see the problem, when i was setting up the motor i had to clearance the bottom of the rocker to clear the retainer, checked it and nothing hit. but i guess when it heated up the aluminum expanded enough to make contact. got a set of rocker shaft shims ordered to raise them up slightly instead of clearancing them all again. and yea im glad i decided to check the valves today, ive been pretty lucky with stuff!