How to determine plug heat range ???

[grego37]

Is there a rule of thumb or formula to determine which heat range to use when choosing spark plugs?

my application is a stroker 408W, 10:1, TFS-R series twisted wedge heads, Crower flat tappet 282/288 DUR 242/250 DUR at .050, .571/.590 lift, Edelbrock Victor jr, Holley 750 DP, 5 speed trans. in a 68 mustang street car

thanks

 

[brianj5600]

http://www.dragstuff.com/techarticles/how-to-read-plugs.html

 

[grego37]

thanks Brian

 

[Maxamil]

If I remember correctly Edelbrock gives you a reccomended heat range sparkplug to use. But I have found no luck finding someone that carries that part #.