501 Series Performance Type 1 Head Bare No seats

AA 501 Series Casting, It is set up to build the performance Head of your needs. It Comes bare with a 12mm plug hole, and with out Seats or Guides. Giving you the the ability to build any possible combo Street/Drag head you want. Seat Pockets start with the Stock 35.5x32 valve size Configuration and can be machined up to the 44x37.5mm The 501 Series Castings come STD with: Increasedmaterialat the intakesurfacegivingyou theabilityto make much bigger ports. Amodernized Combustionchamber, for increased head flow & performance. AsecondFull Fin, soyoucanFlycutyourheads deeper to achieve almost any desired Head CC volume needed. Blocked off rocker stud bosses, to eliminate the O-ring and stoppossibleoil leaks. Long reach 3/4 Inch SparkPlugs, toreduce the chance of cracking betweenthe Valve seat and Plug. Casting: AA 501 Valve Size: N/A Head Bore: 85.5 Plug Size: 12mm (ReplacementNGK Number is D8EA)