Outside Diameter of Outer Spring (in). Number of Springs Per Valve. Speedmaster Pontiac heads include valve sizes at 2.11" Intake, and 1.66" While the 2.11 valves are standard issue, the valve seat can be machined to accept a larger valve with minimal work. CNC Ported heads in this application will soon be available.Speedmaster CNC ported cylinder heads are machined on dedicated 4-axis and 5-axis CNC machining centers to ensure accuracy and cost effectiveness. On the CNC ported versions, combustion chamber, Exhaust and Intake Ports all fully CNC machined for better flow. CNC combustion chambers offer superior control over flame travel and quench area. CNC Ported heads eliminate human error and variation from port to port. Unsurpassed repeatability from one cylinder head to another that is commonly found in "Hand porting & Polishing" Combustion chambers are exact in volume - so every cylinder has the same compression ratio. Each port is the same cross section - so every cylinder can reach higher true RPM potential. CNC machining produces ports and chambers to within tolerances of no more than. 002; in turn every cylinder can reach the same power potential and accurate tuning. HEAD GASKETS The head gasket we recommend for our Pontiac heads is Felpro #10171.
(4.540 Bore) or Fel Pro#1016 (4.300 Bore) INTAKE GASKETS Our heads are manufactured with the Ram Air IV pattern which requires Felpro #1233 gaskets. PUSH RODS Please measure for exact pushrod length once heads and rockers are fully installed. Deck machining, head gasket thickness and rocker arm style will all affect pushrod height. SPARK PLUGS All Speedmaster Pontiac heads use standard 14mm. X 750 reach, 5/8 hex, gasket seat sparkplugs like NGK R5671A-7, Autolite 3924, Champion RC12YC, etc.Remember that higher compression/ boost require a colder heat range sparkplug. HEAD BOLTS / STUDS Our Pontiac heads utilize standard Ram Air Iv head bolts or studs. EXHAUST GASKETS We recommend the use of Edelbrock exhaust gaskets #7281 or any comparable item of your choice. The item "Pontiac 400 455 215cc 72cc Ram Air IV Hydraulic Flat Assembled Cylinder Heads" is in sale since Wednesday, February 19, 2020. This item is in the category "eBay Motors\Parts & Accessories\Performance & Racing Parts\Auto Performance Parts\Engine & Components\Cylinder Heads". The seller is "atracingworld-usa" and is located in Rialto, California. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, China, Sweden, South Korea, Indonesia, South africa, Thailand, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Bahamas, Israel, Mexico, New Zealand, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Kuwait, Bahrain, Croatia, Malaysia, Brazil, Chile, Colombia, Panama, Jamaica, Barbados, Bangladesh, Bermuda, Brunei darussalam, Bolivia, Ecuador, Egypt, French guiana, Guernsey, Gibraltar, Guadeloupe, Iceland, Jersey, Jordan, Cambodia, Cayman islands, Liechtenstein, Sri lanka, Luxembourg, Monaco, Macao, Martinique, Maldives, Nicaragua, Oman, Peru, Pakistan, Paraguay, Reunion, Viet nam, Uruguay.