Spark plug ?

I have W2 heads and have been using RN9YC Champions. Would like to use RC9YC's for the smaller base. Is there any reason why I can't use them?

Nope. I no longer use a 13/16 hex plug unless I absolutely have to do it.

The C and the N are exactly the same except for the hex.


Your life will be much easier with the C plug, especially with the W-2 head. The W-5 was even tighter.

Thank you for your quick reply. Jim

So you can use the 5/8 hex plugs anywhere you are using the 13/16's. Correct heat range of course. Good info Madscientist!

Yup, the smaller hex is easier to deal with, more room at header flanges. Been using C59Y/C61Y (YC has different tip) race plugs for years, kinda spendy though. Batten W2s.
I also use the 5/8 hex on the BB motors, easy choice since their heads are usually aftermarket aluminum.

^^^ I'm sold.