Russ, I know what you're thinking, if the valves were on the same side. On this gravely engine the valves are on opposite sides of the piston. I've heard it called a T-Head engine. Below is a picture of the inside of the head I found on the 'net. It doesn't look like anything will hit. In the factory configuration, the plug gap would be pointing at the intake side, which may help cool off the plug. On mine the plug gap is pointed at the exhaust side. I'll correct it someday, but for now i need it to mow my camp in Vermont. Pretty much the only time i use the gravely.