Cylinder Head Specifications Combustion chamber volume  75cc Intake runner volume  310cc Exhaust runner volume  100cc Intake valve diameter  2 19" Exhaust valve diameter  1 76" Valve stem diameter  11/32" Valve guides  Manganese bronze Deck thickness  5/8" Valve spring diameter  1 55" Valve spring maximum lift   700" Rocker stud  7/16" Guide plate  Hardened steel Pushrod diameter  3/8" Exhaust port location  Stock Spark plug fitment  14mm x 3/4 reach gasket seat INSTALLATION NOTE Match with Edelbrock head gasket sets Bare heads will have valve guides and seats installed but will require final sizing and a valve job to match the valves you will be using Recommended spark plugs are Champion RC12YC or equivalent 14mm x 3/4" reach with flat gasket seat Deck thickness 5/8" rocker stud diameter 7/16" pushrod diameter 3/8" (width of slot in guide plate) Bare heads will have valve guides and seats installed but will require final sizing and a valve job to match the valves you will be using Deck thickness 5/8" rocker stud diameter 7/16" pushrod diameter 3/8" (width of slot in guide plate)