|Chevrolet - 454 HO ENGINE ASSEMBLY|
The Gen VI 454 HO offers outstanding performance and value in an over-the-counter engine package for off-highway applications.
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|454 HO ENGINE ASSEMBLY DESCRIPTION|
7.4L (454ci) HO Engine Assembly
P/N 12568774The new Gen VI 454 HO offers outstanding performance and value in an over-the-counter engine package for off-highway applications. It is the successor to the popular Mark IV LS-6 assembly, which has been discontinued. When equipped with an aftermarket four-barrel carburetor and aftermarket headers, a prototype 454 HO produced 425 horsepower and 500 lb-ft torque.
The 454 HO is based on the “Gen V” big-block V8 that was introduced in 1991. This revised Gen VI engine design also includes a leak-resistant one-piece rear crankshaft seal, relocated oil passages, a redesigned oil filter pad with integral oil cooler connections, cast alum. rocker covers, and 4-bolt main bearing caps.
The 454 HO is completely assembled, less ignition, spark plug wires, carburetor, and exhaust manifolds. It includes a water pump, torsional damper, and automatic transmission flexplate. The 454 HO has a high-rise aluminum for barrel intake manifold and high-performance rectangular port cylinder heads. These cast iron heads have open-style combustion chambers and 2.19/1.88” diameter valves.
With 118cc combustion chambers, the modest 8.75:1 compression ratio loves today’s
pump premium gas and has no appetite for lead, octane boosters or other fuel additives. Its 2.19” intake and
1.88” exhaust valves and high lift .510” I / .540” E roller cam let it breathe with the best of the
early muscle motors. If you want to use you muscle car’s fuel system with a mechanical pump, you can because the
454 HO GEN VI block has a conventional style fuel pump boss.
The 454 HO is not intended for marine use, and should only be used in 1976 and earlier pre-emissions street vehicles or any year off road vehicles.
|454 HO ENGINE ASSEMBLY SPECIFICATIONS|
|Part Number:||Old P/N 24502618, Current P/N 12568774|
|Displacement:||454 cubic inches (7.4-liter)|
|Horsepower:||425 @ 5,250 RPM|
|Torque:||500 @ 3,250 RPM|
|Max. Rec. RPM:||5,500 RPM|
|Block:||P/N 12550307 Cast iron four bolt main caps.|
|Cylinder Bore Dia.:||4.250”|
|Crankshaft:||P/N 14096983 Forged 1053 Steel|
|Connecting Rods:||P/N 10198922 Forged 4340 steel, 7/16” bolts, shotpeened|
|Pistons:||P/N 10215228 Forged aluminum|
|Piston Rings:||P/N 12523921|
|Cylinder Heads:||P/N 14096801 Cast iron rectangular port, open chamber, 118cc combustion chambers|
|Valve Diameters:||2.19” intake, 1.88” exhaust|
|Camshaft:||P/N 24502611 high-performance hydraulic roller tappet|
|Valve Lift:||.511” I, .540” E|
|Valve Springs:||P/N 14097002|
|Valve Lash:||Net Lash|
|Camshaft Duration:||211° I, 230° E at .050” tappet lift|
|Rocker Arms:||P/N 12523976 1.7:1 ratio|
|Flex Plate:||P/N 10185034 14” for automatic transmission|
|Timing Chain:||P/N 10114177 Single roller|
|Damper:||P/N 10216339 8”|
|Intake Manifold:||Aluminum high-rise, for Holley four-barrel|
|Oil Pan:||6 quart with windage tray|
|Oil Pres. (Normal):||40psi @ 2000 rpm|
|Oil Pump Drive:||P/N 3860365 Shaft and P/N 3764554 Sleeve|
|Fuel Pres. Required:||5 to 8.5psi|
|Spark Plugs:||MR43T Gap .045 HEI or .035 for STD distributor|
|Spark Timing:||4° BTDC|
|Technical Notes: For manual transmission applications, use flywheel P/N 14096987 and a suitable 11” clutch assembly. Distributor P/N 1104067 or melonized distributor gear P/N 10456413 must be used on all crate engines with steel camshafts.|
|PARTS THAT WILL WORK WITH THE 454 HO|
|High Torque Mini Starter:||High Power, compact design P/N 123361146|
|HEI Distributor:||P/N 1104067|
|Air Cleaner:||Chevrolet Logo 14” Hi Performance Air Cleaner P/N 12342080|
|Roller Rocker Arms:||1.7:1 ratio full roller design (Qty. 16) P/N 12361323|
|Stud Package:||Rocker Arm Stud Kit (Qty. 16) P/N 12495518|
|Valve Covers:||Tall Chrome, provides clearance for roller rocker arms. P/N 12342099|
|Spark Plug Wires:||Chevrolet Logo 8mm High Performance P/N 12361052|
|Oil Pan:||4 Quart P/N 12495360|