The 454ci big block Chevy engine was first produced in 1970 by lengthening the stroke of the 427ci BBC engine from 3.76- to 4.00-inches, while maintaining the same 4.25-inch cylinder diameter. Performance enthusiasts and engine builders have taken that increase several steps further since, including increasing the displacement to 496ci. This stroker combination is achieved by increasing the factory bore to 4.31-inches and installing a 4.25-inch stroke crankshaft. This combination is not to be confused with GMs late-model production 8.1L Vortec engine that also had a displacement of 496ci. The 8.1L uses a different bore and stroke, and is a low-performance truck engine.
Things You'll Need
- Chevrolet 454ci engine/donor core
- 496ci rotating assembly (crankshaft, pistons and rods)
- Engine overhaul kit (gaskets, rings, etc.)
- Performance engine assembly manual
- Assembly tools
Locate a serviceable 454ci engine. Completely disassemble the engine. The original crankshaft, pistons and connecting rods will not be used, but the remaining components will be. If reusing the original cylinder heads, take the heads and engine block to a reputable machine shop for cleaning, inspection and machine work.
Order a 496ci rotating assembly. These kits include the longer-stroke crankshaft, larger-diameter pistons and longer connecting rods. Many rotating kits include rings and bearing inserts, as well. Be certain to specify the proper type of crankshaft balance to be used -- internally or externally balanced. Factory 454 engines use external balancing weights on the harmonic balancer and flywheel. If using a kit that is internally balanced, non-balanced flywheels and harmonic balancers are required.
Instruct the machinist to check the alignment of the main bearing bores and machine to specified tolerances, if needed. It's also a good idea to have the cylinder block deck machined so that it's surface is flat and square relative to the crankshaft centerline. Have the cylinder bores of the block increased to a diameter of 4.31-inches. The machinist will need the pistons to properly fit them to the cylinder bores. It's recommended that the machinist check all measurements of the crankshaft and rods to ensure that they are correct, as well. Balancing the entire rotating assembly is suggested, but not required unless severely out of recommended tolerances.
Have the cylinder heads cleaned and reconditioned with a performance valve job. If they are to be used in a standard-performance application -- such as a tow truck -- the original 454 heads will perform well. If this is a high-performance build, the heads should be ported and modified to meet the increased airflow requirements of the larger displacement. Alternately, new aftermarket heads can be selected that are more suitable, and may be justified in light of the extra machining and labor costs required to modify the factory 454 castings.
Assemble the engine according the engine-building manual, taking care to follow all clearance-measuring and fastener-tightening values.
Tips & Warnings
- An alternative to assembling the engine yourself is to have the machinist complete this for you. If there are any final fitment issues, this can be an advantage. Additionally, the cost for doing this may also be justifiable.
454 Engine Build Specifications
A 454 cubic inch small-block engine can be custom built to match or exceed the specifications of the original Chevrolet 454 big-block....
How to Set the Timing on a Chevy 454
The timing on a stock Chevy 454 should be 4 to 6 degrees initial timing, 16 degrees under vacuum advance and 32...
How to Rebuild a 454 Engine
The 454 is the most common member of Chevrolet's big block engine family. Rebuilding a 454 is easy, provided that you know...
How to Turn a 454 Engine Into a 502 Engine
Changing a 454 cubic inch engine into a 502 cubic inch engine requires making the combustion chambers bigger by boring metal from...
How to Build a 540 Chevy Big Block
Big-block Chevrolet engines have been manufactured by General Motors in production displacements up to 454ci, as well as the last 496ci, 8.1-liter...
How to Build a 496 Big Block Chevy
The 496 cubic-inch big-block Chevy (BBC) was one of the earliest BBC "stroker" engines designed by performance enthusiasts with combinations of both...
496 Ci Engine Specs
The 496 Ci Engine is a top-notch Chevy engine designed for motor boats. The Big Block Chevy (BBC) model is a large,...