I have stage 1 crower cams on my B16A/B20 block engine. Just wondering,is it possible adjusting the valve clearance too close can cause the pistons hitting my cylinder head? Cause it happened too me after I rev the engine hard (close to 8K rpms) and then the engine starting too overheat. I took it to a mechanic and 4 of my exhaust bolts is loose and all 4 my pistons (intake side) were scratch little bit. But all 5 of my intake side bolts are fine.

 

.... your valve lash can be REALLY far off... or your timing belt could be jumping teeth to the point where your actually letting the valves slam into the pistons... i don't think it's possible for pistons to hit the head... makes no sense