GM Performance Cylinder Head, Vortec, Assembled, Cast Iron, 64cc Chamber, 170cc Intake Runner,
Part Number:GMP-12691728
GM Performance Cylinder Head, Vortec, Assembled, Cast Iron, 64cc Chamber, 170cc Intake Runner, Chevy, Small Block, Each (PART #GMP-12691728)
GM Performance cast iron Vortec cylinder heads will fit 1958 and later small block Chevy engines, and offer a 20 to 40 hp increase over earlier cast iron small block heads. Features include fast burn combustion chambers, and a high-velocity port design. They require the use of a Vortec-style intake and self-aligning rocker arms, and come complete with valves, springs, and retainers.
SPECIFICATIONS |
|
| Brand | GM Performance |
| Manufacturer's Part Number | 12691728 |
| Part Type | Cylinder Heads |
| Product Line | GM Performance Vortec Cylinder Heads |
| Combustion Chamber Volume (cc) | 64 |
| Intake Runner Volume (cc) | 170cc |
| Cylinder Head Style | Assembled |
| Cylinder Head Material | Cast iron |
| Camshaft Style | Hydraulic flat tappet |
| Intake Port Shape | Rectangular |
| Intake Valve Diameter (in.) | 1.940 in. |
| CNC-Machined Combustion Chamber | No |
| CNC-Machined Intake Runner | No |
| CNC-Machined Exhaust Runner | No |
| Intake Port Location | Standard |
| Exhaust Port Shape | Rectangular |
| Exhaust Port Location | Standard |
| Spark Plug Style | Straight |
| Intake Valves Included | Yes |
| Exhaust Valves Included | Yes |
| Exhaust Valve Diameter (in.) | 1.500 in. |
| Valve Springs Included | Yes |
| Maximum Valve Lift (in.) | 0.475 in. |
| Outside Diameter of Outer Spring (in.) | 1.250 in. |
| Damper Spring Included | Yes |
| Number of Springs Per Valve | Single |
| Retainers Included | Yes |
| Retainer Material | Steel |
| Locks Included | Yes |
| Lock Style | 7 degree |
| Valve Stem Seals Included | Yes |
| Valve Stem Seal Style | Positive stop |
| Rocker Arm Studs Included | Yes |
| Rocker Arm Nut Thread Size | 3/8 in.-24 |
| Rocker Arms Included | No |
| Rocker Arm Nuts Included | No |
| Guideplates Included | No |
| Valve Cover Mounting Style | Centerbolt |
| Accessory Bolt Holes Drilled | Yes |
| Valve Guides Included | Yes |
| Valve Guide Material | Manganese bronze |
| Valve Seats Machined | Yes |
| Cylinder Head Color | Natural |
| Steam Holes Drilled | No |
| Oiling Style | Through pushrod |
| Machined for O-Ring | No |
| Heat Crossover | No |
| Remanufactured | No |
| Quantity | Sold individually. |
| Notes | Max Valve Lift as delivered is 0.475 in. and anything above requires machining of the valve guide bosses and checking valve seal-to-valve spring retainer clearance. The installed valve springs have approximately 80 lbs. seat pressure and 195 lbs. open at 0.450 in. lift and are compatible with the stock hydraulic roller camshaft and most hydraulic flat tappet camshafts. |
