What spark plugs for 340

[johnnycuda]

The original plugs were RN9YC

I didn't use the resister plugs either . But that would just be more confusing for some members. The non resister plugs also interfere with some of today's later ignitions and Stereos.

So these are my best option? i like the old school ideas

 

[Woodys_Cuda]

I have a similar build (68 block) and running N9YC and need 94 octane fuel.. I tried hotter plugs and went back to the N9YC.