The stock spark plug for a 235 was AC-44 for regular (non-Ethanol) gasoline.

Today:
AC-R43S = colder range spark plug
AC-R45S = hotter range spark plug

Which one is best for your engine depends on which gasoline type you plan to run.
Ethanol generates more heat than non-Ethanol.


"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."