The 454 HO offers tremendous value in a big block crate engine. Based on the Gen VI block, this 425 horsepower cast iron head engine is a great choice for that muscle car in the garage. Details: The 454 HO offers tremendous value in a big block crate engine. Based on the Gen VI block, this 425 horsepower cast iron head engine is a great choice for that muscle car in the garage. We?ve heard of several of our customers replacing their rare matching number 396, 427 or 454 with our 454 HO in order to drive their car on today?s gasoline without fear of destroying their classic engine.p>The HO stands for high output, it also stands for big valves, rectangular ports, forged pistons, forged steel crankshaft, forged connecting rods and four bolt mains. Sounds a lot like the performance big blocks of the late 60?s doesn?t it? When you add in the steel roller camshaft, shotpeened rods, windage tray, one piece rear main seal and high speed single roller timing chain, it starts to sound more like the performance big block of the new millenium. And it is. The 454 HO makes 500 ft.lbs of torque with its rectangular port open chamber cylinder heads. With 118cc combustion chambers, the modest 8.75 to 1 compression ratio loves today?s pump premium 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"/.540" roller cam let it breathe with the best of the early muscle motors. With your carburetor, HEI distributor, exhaust system and bright red ?67 Corvette coupe (sold separately 34 years ago), you?ve got a muscle cruiser worthy of your time, effort and expertise. And, if you want to use your muscle car?s fuel system with a mechanical fuel 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 Technical Information Horsepower 425 @ 5250 RPM Torque 500 @ 3250 RPM Max. Recommended RPM 5500 Compression Ratio 8.75:1 Block 12550307 Cast iron - four bolt mains Crankshaft 14096983 Forged Steel Connecting Rods 10198922 Forged Steel Pistons 10215228 Forged Aluminum Piston Rings 12523921 Camshaft 24502611 Hydraulic roller Lift: .510" I, 540" E. Duration @ .050: 211º I, 230º E. Timing Chain 3891519 Single Roller Cylinder Heads 14096801 Cast iron 118cc combustion chambers Intake Valves 14097045 2.19" Exhaust Valves 14097049 1.88" Valve Springs 14097002 Rocker Arms 12523976 1.7:1 Flexplaate 10185034 14" Torsional Damper 10216339 8" Oil Pump Drive 3860365 Shaft and 3764554 Sleeve Valve Lash Net lash Fuel 92 Octane Spark Plugs MR43T Gap .035 #10 Rapidfire Gap .035 Ignition Timing 4º BTDC Technical Notes: For manual transmission applications use flywheel 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. Customize your 454 HO with GM Performance Parts Below is a sample of the parts that you'll find throughout our catalog to help you complete your crate engine installation or customize your crate engine for your specific application. 12361146 High torque Mini Starter High Power, compact design. Technical Note: This starter is not recommended for competition. 1104067 HEI Distributor 12342080 Chevrolet Logo 14" Hi Performance Air Cleaner 12361323 Roller Rocker Arms - 1.7 ratio full roller design (Qty 16) 12495518 Stud Package, Rocker Arms (Qty 16) 12342099 Tall Chrome Valve Cover - Provides clearance for roller rocker arms 12361052 Chevrolet Logo 8mm High Performance Spark Plug Wires 12495360 4-Quart Oil pan