What spark plugs are you using ?

[gaddied]

So what spark plugs are you using in your 1970 340 4 barrel ?
The service manual  lists N9Y while Champion lists N12YC ??
Isn't  the N12YC to hot of a spark plug ?

[chargerdon]

Im using champion RN14yc

[73_Cuda_4_Me]

I have a 70 340 in my 73, and run the 12YC... no problems at all with color or heat range... dark tan on insulators, just normal cruising, mostly stock engine...