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Important Technical Note: Use of the adjustable Mark IV cylinder head is not recommended with the new "Gen V engine". Changes in the configuration of the "Gen V's" coolant transfer passages allows coolant to seep into the lifter valley when the Mark IV head is used. All Gen VI block will accept Mark IV cylinder heads because the water coolant holes were decreased in size. These cylinder cases all have aluminum front covers with six bolts, not the sheet metal front cover. Mark IV camshafts, water pumps, intake manifold, distributor and clutch housings can be used with the new "Gen V" engines.

Technical Notes: Use of the adjustable Mark IV cylinder head is not recommended with the new "Gen V engine". Changes in the configuration of the "Gen V's" coolant transfer passages allows coolant to seep into the lifter valley when the Mark IV head is used. Mark IV camshafts, water pumps, intake manifold, distributor and clutch housings can be used with the new "Gen V" engines. The symmetrical port cylinder head is sold without seats and guides. Its raised ports and deep valve bowls require valves which are .800" longer than production valves. This head requires a fabricated intake manifold, aftermarket rocker arms, aftermarket studs or head bolts, and special pistons. Chevrolet Bow Tie rocker covers can be installed on symmetrical port cylinder heads.

10051129 Unmachined Symmetrical Port Cylinder Head 1965-90 This unmachined casting of the Bow Tie symmetrical port head is intended for cylinder head specialists and competition engine builders who want to make extensive modifications. The Aluminum alloy specified for this raw cylinder head makes the casting slightly harder and easier to weld than a fully machined version. Technical Notes: Use of the adjustable Mark IV cylinder head is not recommended with the new "Gen V engine". Changes in the configuration of the "Gen V's" coolant transfer passages allows coolant to seep into the lifter valley when the Mark IV head is used. Mark IV camshafts, water pumps, intake manifold, distributor and clutch housings can be used with the new "Gen V" engines. Raw symmetrical port heads are cast from 355-T6 aluminum. The intake runners in raw castings are slightly smaller than the ports in finished heads.

10093385 Cylinder Head 1965-90 This aluminum cylinder head is designed for the Chevrolet Big-Block engine and bears a Pontiac logo. It is a "raw" (unmachined) head with 15º valve angles with spread intake runners. Use on Mark IV blocks only.


10093386 Cylinder Head 1965-90 This big block aluminum cylinder head developed by Pontiac is fully machined and has 15º valve angles with spread port intake runners. It is for use with all Chevrolet Big-Block engines. Use on Mark IV blocks only. Technical Notes: Intake manifold must be fabricated ; use a Felpro gasket.


12363390 Complete Oval Port Aluminum Head 2.25" Valves This head is identical to P/N 12363399, except it has 2.25" stainless steel intake valves, and 1.88" stainless steel exhaust valves with 11/32 stems. It also includes high performance valve springs, valve spring caps, keys and valve stem seals. These heads are designed for high horsepower 396, 427, 454, and 502 engines. Technical Notes: For 502ci engines, use head gasket kit P/N 12363411 and no sealant on the head bolt. For all big-block engines, use intake manifold gasket kit P/N 12366985, with intake bolt kit P/N 12367959, and cylinder head bolt kit P/N 12367779. Use the following components for service: P/N 12366987 Intake Valve 2.25"; P/N 1366988 Exhaust Valve 1.88"; P/N 12462970 Valve Spring; P/N 12366990 Valve Spring Retainer; P/N 3875916 Valve Spring Shim (Requires 2); P/N 12366992 Valve Lock; P/N 12366993 Oil Seal.


12363392 Complete Oval Port Aluminum Head 2.19" Valves This head is identical to P/N 12363399, except it has 2.19" stainless steel intake valves, and 1.88" stainless steel exhaust valves with 11/32 stems. It also includes high performance valve springs, valve spring caps, keys and valve stem seals. These heads are designed for 396, 427, 454, and 502 engines. Technical Notes: For 502ci engines, use head gasket kit P/N 12363411 and no sealant on the head bolt. For all big-block engines, use intake manifold gasket kit P/N 12366985, with intake bolt kit 12367959, and cylinder head bolt kit P/N 12367779. Use the following components for service: P/N 12366986 Intake Valve 2/19"; P/N 12366988 Exhaust Valve 1.88"; P/N 12462970 Valve Spring; P/N 12366990 Valve Spring Retainer; P/N 3875916 Valve Spring Shim (Requires 2); P/N 12366992 Valve Lock; P/N 12366993 Oil Seal.


12363399 Signature Series Aluminum "Oval Port" Cylinder Head These oval port cylinder head will fit all 1965-1996 Mark IV and Gen V or VI 396 thorough 502 cubic inch big block Chevrolet engines. They are fully machined with semi-finished Bronze Alloy guides and semi-finished valve seats that use 2.19/1.88" valves. These high velocity "290cc intake runners enhance mid range throttle response and torque. The exhaust runner volume is 110cc., the 110cc semi open combustion chamber design will make a very streetable compression ratio. Spring DIA is 1.55", with 7/16" rocker stud holes. These accept all stock accessory brackets except Gen V where the bracket holes have been enlared to 7/16". The roller studs and exhaust bolt holes are heli-coiled for strength. Technical Notes: These heads are made from 356-T6 aluminum alloy. The 9/16" deck surface is for maximum strength and greater head gasket sealing . Designed for 3/8" push rod diameter. These heads require cylinder head bolt kit P/N 12367779. Use the following performance head gasket 1965-90 with standard bore to 4.370" use P/N 12363414 and with 4.47" to 4.540" use P/N 12363413, and with GEN V 1991-98 engines with standard to 4.370" use P/N 12363412, with bores of 4.47" to 4.54" use gasket P/N 12363411. The semi-finished bronze guide can be finished either 11/32" or 3/8" . The inter-locking hardened valve seat will accept leaded or unleaded gas. Use intake gasket P/N 12366985.


12363400 Complete Rectangular Port Aluminum Head 2.25" Valves This head is identical to P/N 12363410, except it has 2.25" stainless steel intake valves, and 1.88" stainless steel exhaust valves with 11/32 stems. It also includes high performance valve springs, valve spring caps, keys and valve stem seals. These heads are designed for high horsepower 396, 427, 454, and 502 engines. Technical Notes: For 502ci engines, use no sealant on the head bolts. For all big-block engines, use intake manifold gasket kit P/N 12366985, with intake bolt kit P/N 12367959, and cylinder head bolt kit P/N 12367779. Use the following components for service: P/N 12366987 Intake Valve 2.25"; P/N 12366988 Exhaust Valve 1.88"; P/N 12492970 Valve Spring; P/N 12366990 Valve Spring Retainer; P/N 3875916 Valve Spring Shim (Requires 2); P/N 12366992 Valve Lock; P/N 12366993 Oil Seal.


12363408 Aluminum Cylinder Head, NHRA Legal This new aluminum cylinder head is a replacement for the 1969 L88 head P/N 14011076 used on 1969 Camaro and 1968-71 Corvette vehicles. This head is similar to P/N 12363410 except that the intake ports are as cast, not CNC'd. The valve seats can be machined to 2.19" intake and 1.88" exhaust or larger. The rectangular port intake volume is 315cc, with square exhaust ports. The combustion chamber is 118cc and the valve guides start at 11/32", but can be machined to 3/8". Technical Notes: The casting is P/N 12363401.



12363410 Signature Series Aluminum "Rectangle" Cylinder Head This Cylinder head fits all 1965-1996 Mark IV and GEN V and VI 396 thu 502 cubic inch Big Block Chevrolet engines. They are fully machined with semi-finished bronze alloy guides and semi-finished valve seats that use 2.19/1.88" valves. These high velocity 315cc long intake runner and 300cc short runners enhance mid-range throttle response and torque. The exhaust runner volume is 110cc. The 118cc semi-open combustion chamber design will make a very streetable compression ratio. Spring DIA is 1.55", with 7/16" rocker stud holes. These accept all stock accessory brackets except GEN V where the bracket holes have been enlarged to 7/16". The rocker studs and exhaust bolt holes are heli-coiled for strength. Intake and exhaust ports are in stock locations. Technical Notes: These heads are made from 356-T6 aluminum alloy. The 9/16" deck surface is for maximum strength and great head gasket sealing. Designed for 3/8" push rod diameter. These heads require cylinder head bolt kit P/N12367779. Use the following performance head gasket 1965-1990 with standard bore to 4.370" use P/N 12363414 and with 4.47" to 4.540" use P/N 12363413, and with Gen 1991-1996 engines with standard to 4.370" use P/N 12363412, with bores of 4.47" to 4.54" use gasket P/N 12363411. The semi-finished bronze guide can be finished either 11/32" or 3/ 8" . The interlocking hardened valve seat will accept leaded or unleaded gas. Use intake gasket P/N 12511789.


12363425 Signature Series Racing Bow Tie Cylinder Head 1965-96 This aluminum Bow Tie cylinder head offers a significant performance improvement over production castings. Bow Tie heads are recommended for large displacement competition engines 1965-1996 Mark IV, Gen V and Gen VI. The Bow Tie head's intake runners are raised .100" above the standard port location and enlarged to improve airflow. The rectangular exhaust ports are raised .750" from the standard position to reduce turbulence in the runners. Vanes in the floor of the exhaust ports reduce turbulence (these are referred to as "W" ports by some Chevrolet enthusiasts). The big-block Bow Tie head has unique 115cc open combustion chambers. Material was added between the valve seats to reduce the combustion chamber volume, and the chamber walls adjacent to the valves are not relieved. The seat inserts and bronze valve guides are semi-finished for 2.19" diameter intake valves and 1.88" exhaust valves. The rocker arm stud bosses are reinforced and heli-coiled to improve reliability with racing valve springs. The rocker cover rails are raised .250"; standard valve covers can be installed. Two additional head bolt holes are drilled in valley area. Technical Notes: The Bow Tie cylinder head's raised intake runners require valves which are .400" longer then the stock. The valve spring seats can be machined .200" ; check the valve spring installed height after machining the spring pads. Pushrod guideplates (P/N 3860038) must be ground for clearance before installation. The upper intake manifold bolt holes are not drilled in Bow Tie cylinder heads. Ports in production and after market intake manifolds must be modified to match the intake runner entrances. This head's exhaust flange bolt holes are in the standard big-block location; drill and tap new bolt holes in the exhaust manifold flange or modify the header flanges to center the exhaust pipes over the port exits the deck thickness is 9/16" for maximum strength. The four head bolt bosses adjacent to the exhaust ports are taller than production heads: for 3.38" use 4.19" bolt(6)or 4.50" bolt(2); for 4.69" use 5.50" bolt(4); for 1.38" use 2.19" bolt(4). The heads are cast from 356-T6 material and the casting P/N is 14044861, same as the first design heads.


12480010 DRCE Racing Head Semi-Finished This new DRCE semi-finished head is for the new 4.900" bore center blocks. It is the same as P/N 24502585 except it is a semi-finished "cubed" head. This new DRCE semi-finished head is for the new 4.900" bore center blocks. For raw casting see P/N 234502585.


14044876 Cylinder Head Casting This raw casting was used to make first design cylinder head assembly 14044861 or 14044862. This casting has no machining on it.

14096801 Complete Gen V & Gen VI Cylinder Head These are the same as 14096802 except they include the valve, spring and caps. For 1991 and later Gen V & Gen VI engines. Technical Notes: These are "Iron" heads with rectangular intake ports.


14096802 Cylinder Head 1991-92 This "Iron" cylinder head is intended for use with the Gen V & Gen Vi design 454 (7.4-liter) big-block HO V8 engine (part P/N 24502618) and 502 engine (P/N 24502620). The heads are 118cc open chamber with 2.18" intake valves and 1.88" exhaust valves with rectangular intake ports. They have 3/8" rocker bolt holes.


24502585 DRCE2 Cylinder Head This GM Performance / DRCE2 Cylinder head was designed specifically for the DRCE2 block P/N 24502572. It is intended for professional competition applications. It is designed to comply with NHRA Pro-Stock rules for 500 cu. in. engines with 4.900" cylinder bore spacing. The DRCE2 heat treated head casting is sold as P/N 24502585 or as a semi-finished "cube" with bolt holes as P/N 12480010. Special DRCE2 cylinder head features include: High capacity water jacket that is self purging, symmetrical port layout with ample wall material for custom porting designs, thick deck (.850) surface without cast-in combustion chambers to facilitate "angle milling" without weakening the deck. Reduced weight casting to minimize CNC machine time. The DRCE2 cylinder head casting is produced from 357-T6 aluminum with provisions for intake valve angles of 10-14 degrees and canted 5 degrees. The exhaust valve angles of 9-5 degrees with a 2.5 degree cant. The casting is "robust" to provide adequate cylinder head clamping. A typical CNC prepared cylinder head without valves and valve train has a weight of 40 lbs. This DRCE two-head requires aluminum die cast valve cover P/N 12370852.


6260482 Open Chamber Cylinder Head (Cast Iron) 1968-90 This is Chevrolet's best cast iron cylinder head for high-performance big-block V8s. It offers exceptional power at an economical price. This casting has 118cc open combustion chambers that reduce shrouding at high valve lift and improve engine airflow. The seats are ground for large 2.19" diameter intake valves and 1.88" exhausts. This high-performance head has rectangular intake ports and square exhaust ports. It is machined for 7/16" screw-in studs and guideplates (not supplied). Technical Notes: (see "Technical Notes" at the beginning of the Cylinder Head Group section for important information) This head was installed on LS-6 engine assembly P/N 366250 and LS-7 engine assembly P/N 3965774. It can be used with both closed and open chamber pistons to produce various compression ratios. Casting number 14096188 or 6272990. Cannot be used on Gen V engines because of upper water hole alignment. Open Chamber Design.
Chevrolet Big Block V8 Cylinder Heads Quick Reference Chart Part Number Description Casting Number Material Combustion Chamber Valve Diameters Intake Vol. (cc) Intake Port Type Exhaust Port Notes 6260482 Service Replacement 6272990 or 14096188 Cast Iron Open 118cc I: 2.19"
E: 1.88" 325 Rect. Square Used on LS-6 and LS-7. Open or closed chamber pistons. Originally produced 1968-71. 14096802 Service 14097088 Iron Cast Open 118cc I: 2.19"
E: 1.88" 325 Rect. Square use with Gen V big-block engine P/N 24502618-20 "BARE" 14096801 Service 14097088 Cast Open 118cc I: 2.19"
E: 1.88" 325 Rect. Square Use with Gen V big-block engine P/N 24502618-20. Complete with springs and valves. 12552888 Service Replacement 10114156 Open 118cc Cast Iron I: 2.07"
E: 1.72" - Round Square use with Gen VI big-block engine P/N 12361054. Complete with springs and valves. 12363399 Bow Tie Performance 12363391 Aluminum A356-T6 Semi-open 110cc I: 2.19"
E: 1.88" 290 Oval Square Standard intake and exhaust port locations. No valves. 12363392 Bow Tie Performance 12363391 Aluminum A356-T6 Semi-open 110cc I: 2.19"
E: 1.88" 290 Oval Square Head includes springs and valves. 12363390 Bow Tie Performance 12363391 Aluminum A356-T6 Semi-open 110cc I: 2.25"
E: 1.88" 290 Oval Square Head includes springs and valves. 12363408 Bow Tie NHRA Legal 12363401 Aluminum A356-T6 Semi-open 118cc I: 2.19"
E: 1.88" 315 Rect. D-Port Legal for NHRA Competition - Replaces RPOL88 Head 12363410 Bow Tie Performance 12363401 Aluminum A356-T6 Semi-open 118cc I: 2.19"
E: 1.88" 315 Rect. Square Standard intake and exhaust port locations. No valves. 12363400 Bow Tie Performance 12363401 Aluminum A356-T6 Semi-open 118cc I: 2.25"
E: 1.88" 315 Rect. Square Head includes springs and valves. 12363425 Bow Tie Performance 14044861 Aluminum A356-T6 Open 115cc I: 2.19"
E: 1.88" 380 Rect. Rect. w/vane Second design raised intake and exhaust port. No valves. 10051128 Symmetrical port Bow Tie 10051128 Aluminum A356-T6 Semi-open 72cc NA400 Round Rect. Evenly spaced intake runners, raised exhaust ports. Pro Stock head. No seats and guides. 10051129 Raw symmetrical port Bow Tie 10051129 Aluminum A356-T6 Semi-open 72 7scc NA400 Round Rect. Unmachined casting 10045427 Pontiac Super Duty 10045427 Aluminum Open 91c I: 2.40"
E: 1.90" 460 Rect. D-shaped Pontiac Motorsports head for 600ci racing engines. Guides not installed. 10093386 Pontiac Super Duty Aluminum 61.4cc I: 2.40:
E: 1.90" 365 Rect. D-shaped Pontiac Motorsports head for all Chevrolet big-block engines. 10093385 Pontiac Super Duty Aluminum 60.4cc I: 2.40"
E: 1.90" 420 Rect. D-shaped Pontiac Motorsports head for all Chevrolet big-block. No machining. 14044876 Bow Tie 14044861 Aluminum A356-T6 Open 105cc Not Machined 380 Rect. Rect. w/vane Raised First design "casting only" intake and exhaust. 12480010 DRCE Semi-Finished N/A Aluminum A356-T6 Semi-Machined N/A Rect. Rect. use with 4.900" bore centers 24502585 DRCE Raw casting N/A Aluminum A356-T6 Raw casting N/A Rect. Rect. Use with 4.900" bore centers.