Black powder coated. Stock style high performance bolt-on replacement for Twin Cam models; compatible with stock manifolds; rocker boxes and exhausts. Heads are 79cc and take stock diameter 1.940" intake and 1.575" exhaust valves. Head will handle up to .650" lift and are set-up to be used with up to .186" intake & .179" exhaust TDC lift in combination with stock pistons. This allows the use of S&S 510; 570 and 585 camshafts. Heads can be decked up to .060" to increase compression but then valve lift clearance checks are required. Expected compression ratio''s for unmodified heads with stock pistons will approximately be 9.8 CR (96"); 10.2 CR (103"); 11.1 CR (103" with pop-up S&S pistons) and 10.8 CR (110"). Heads come complete with valves; guides and valve springs installed. Note: Compatible with stock rocker covers but S&S compression release or S&S easy start cams must be used to retain easy electric starting due to the higher compression ratio. Heads are machined to accept compression releases and manual compression release plugs are included. Note: Not compatible with stock rocker cover gaskets. Must use special 532583 rocker cover gasket kit with stock rocker covers. These are required for correct engine breathing.