Page 148 of GM Performance Parts 2006 Catalog by GM Parts Direct

Small and Large Port Vortec Bowtie Heads (intake). Bare head shown. Small Port Vortec Bowtie Head (exhaust). Bare head shown. Large Port Vortec Bowtie Head (exhaust). Bare head shown. 146 Small and Large Port Vortec Bowtie Heads (combustion chamber) VORTEC BOWTIE HEADS These are GM Performance Parts most powerful cast iron cylinder heads designed for street or racing applications in the 400-450 horsepower range. As an upgraded production head, they come with bigger valves, a thicker deck surface, and a 66 cc combustion chamber, which offer tremendous low-lift flow numbers. They offer you Fast Burn performance in an affordable cast iron head that are often used for short-track racing applications. Vortec Head Technical Notes: Cast iron small runner or large runner heads 66 cc combustion chamber, .450" deck thickness Straight spark plugs No heat risers Machined for 2.00"/1.55" valves Hardened exhaust valve seats 0.530" max valve lift (without modifications) Drilled and tapped for screw-in studs (7/16-14) Dual bolt patterns for perimeter bolt and center bolt valve covers Dual bolt patterns for both Vortec and early model intake manifolds (use early model P/N 10051103 or Vortec design P/N 12366573,P/N 12496820, P/N 12496821, P/N 12496822, or P/N 12499371) Use production intake gasket P/N 12529094 for Vortec intakes or dual bolt pattern intake gasket P/N 12497760 for either early model or Vortec design manifolds Vortec logo (intake port roof), GM logo (intake port floors) Bowtie logo (exhaust side) are cast-in A. 25534421 Small Port Vortec Bowtie Head Assembly Completely assembled, ready to bolt-on 185 cc intake port 65 cc exhaust port Uses Fel-pro #1470 exhaust gasket Bare head P/N 25534351 available separately B. 25534431 Large Port Vortec Bowtie Head Assembly Completely assembled, ready to bolt-on 215 cc intake port 84 cc exhaust port Uses Fel-pro #1470 exhaust gasket, may require minor trimming Bare head P/N 25534371 available separately These heads are assembled with the following components: 25534407 Intake Valves 10212808 Valve Spring Retainers 25534408 Exhaust Valves 10212810 Valve Stem Seals 12551483 Valve Springs 12564852 Valve Locks 12552126 3/8 Rocker Studs 1Larger intake and exhaust ports allow for more volume of air to pass through the engine. The more air you flow, the more power you can make. CHEVY SMALL-BLOCK V-8 A B A, B A, B

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