Genuine Autolite spark plugs.  Set of 8.

Gap .044" (1.1mm)

Suits many alloy aftermarket  cylinder heads fitted to many engines like Ford, GM & Mopar, including AFR Cylinder heads used on many SBF applications. Refer your instruction sheet for confirmation.

From the AFR Cylinder head instructions sheet for most of the SB Ford Windsor cylinder heads. Check your particular instructions if you're unsure:

SPARK PLUGS: Use 14mm x 3/4” reach gasketed spark plugs, no tapered seat plugs. Street application use Autolite #3924, for 205cc & 220cc race head use Autolite #3922, or equivalent. Plug selection is of course dictated by many factors including RPM level, compression ratio, and fuel type. Forced induction or nitrous applications usually require 1 to 2 heat ranges colder. Spark plug gap should be determined by the ignition manufacturer.