Spark Plug Heat Ranges & Part #'s
 

Came across this and thought it might help with plug questions

MOTORCRAFT
PART# / HEAT RANGE
AWSF-32C / stock heat range - copper plug
AWSF-22C / 1 Heat range colder - copper plug
AWSFA-12C / 2 Heat range cooler - copper plug
AGSF-32C/ Recommended for FRPP heads(not sure on heat range)


NGK
PART# / HEAT RANGE
TR-55/ 3951/ Stock Heat Range
TR-6/ 4177/ 1 Step Colder
BP7EFS (PN - 3526) BR7EF (PN - 3346) two steps
R5724-8 (PN - 7317) two and a half steps
R5724-9 (PN - 7891) three steps
R5724-10 (PN - 7993) four steps


AUTOLITE
PART# / HEAT RANGE
764s / Stock
103s / 1 heat range cooler
AR94 / 2 heat range cooler
AR93 / 3 heat range cooler
AR92 / 4 heat range cooler


CHAMPION
PART# / HEAT RANGE
Stock is RS12YC
RS9YC 1 step colder

DENSO
PART# / HEAT RANGE
IT16 / stock heat
IT20 / -1 heat range
IT22 / -2 heat range
IT24 / -3 heat range

Wrong Champion number. What you listed was probably a race plug, which won't work w/ the stock ignition system (no resistor). Stock is RS12YC and 1 step colder is RS9YC. I'm assuming 2 steps colder would be RS6YC.

Sorry for the wrong info, I got this from a local forum which is normanlly pretty good for giving the right info.