502 Series Performance Head W/ seats and guides 40 Intake 35.5 Exhaust

Made from an AA 502 Series Casting, It is set up to build the performance Head of your needs. It comes with Seats 40x35.5, Guides, with a 12mm plug hole. The 502 Series comes with our Stage 2 porting with a modernized combustion chamber for increased head flow & performance. There is a second Full Fin, so you can Fly cut your heads deeper to achieve almost any desired Head CC volume needed. Blocked off rocker stud bosses, to eliminate the O-ring and stop possible oil leaks. Long reach 3/4 Inch Spark Plugs, to reduce the chance of cracking between the Valve seat and Plug. Casting: AA 502 Valve Size: 40x35.5 Head Bore: 85.5 Plug Size: 12mm (Replacement NGK Number is D8EA) Head CC's: 55