Modded 360: Not sure of Sparkplug Heat Range

[QuickDart360]

Ok guys and gals! My 360 is beefed up some with 340 X-heads, 292 mopar purple cam ( advanced 4°). KB107 flat top pistons not of actual compression, Victor 340 intake. 727 trans with an FTI 9.5" 3400-3600 stall converter. 3.91's out back. So my old set up was a 280 mopar cam and 3.55s then. That set I ran rn12yc plugs and did good. With this new set up do I go one step colder (rn11yc's)? Or stick with the rn12's? Please fill me in!

 

[QuickDart360]

Meant to say not sure of my actual compression 9:5 or 9:8 maybe? Just not sure.

 

[fishmens67]

Stick with the RN12. you won't know the proper heat range until you read the plugs after running the engine.

 

[QuickDart360]

Ok sounds reasonable. I have not yet fired engine in this new configuration.

 

[Syleng1]

Drive her around a bit and then check plugs. IMHO.