Spark plug advice

dartfreak75 said
This might be a stupid question but how do you know the heat range I'm looking at the champion 405 copper plus plugs I dont see a heat range in the description

What is the number designation of the plug? 405 is the stock number.

You should be looking at an RC12YC or equivalent IIRC your engine.

R = resistor
C = plug type (3/4 reach, 5/8 hex is a C)
12 = heat range
Y = tip length
C = copper core

The C and the N series Champions are the exact same plug EXCEPT the N series is a 13/16 hex and the C is a 5/8 hex.

I’m not a fan of the 13/16 hex. I was hoping that Champion will kill the N series plugs and keep some others they have evidently killed.