Auto light spark plug

[Norcalputput]

I am reassembling my engine with a Honda flat top piston and running the math for interference before I seal the deal with the first rip of the cord has any one had to shim the spark plug up in the chamber to avoid hitting the piston

I have .040" clearance piston to head and the spark plug hangs .056" below the head should I shim it below the head or change the plug style


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[vwfan79]

I have two heads one milled .065 and the other .075 and was running flat tops in both motors and had to put a washer to shim the plug due to it hitting the piston.

 

[Norcalputput]

Where would be the best has any one recorded a difference in power I originally bought the spark plug due to it takes up cc's in the head...


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[vwfan79]

I haven't noticed any difference in power, a shorter plug or a shim your basically doing the same thing.

 

[mikeholt25]

yes shim it. or youll b replacing cracked piston, put play doe on the piston install head and put spark plug in turn engine over acouple times with your hand remove head check your clearance play doe or clay works great