How Do You Find Out The Right Heat Range For Spark Plugs For A 72 Chevy 350 Engine 120 Psi Of Compression

I’m having problems with it carbon fouling , loosing cylinders, rough idle in gear. Thinking it was a vacuum leak replaced the intake gasket and still having the problems. I’m thinking its either the spark plugs (R44T) or putting a hotter coil to fix the problem.
Before I go buy something I don’t need , Can anybody help me please.

Answers for The Question

  1. Dan B
  2. cdever5
  3. paul h
  4. mister ss
  5. sidecar0