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 Vortec engine (for trucks). The common theme in each increase in displacement has been to increase both the cylinder bore and crankshaft stroke within the practical limits of the factory cylinder block. However, displacements of more than 500ci -- using bores much beyond 4.25-inches -- typically exceed the bore diameter limitations of the production block. Since the 540ci stroker uses a bore of 4.5-inches and a stroke of 4.25-inches, an aftermarket block is needed.

Things You'll Need

  • Aftermarket big-bore cylinder block
  • 540ci rotating assembly (crank, pistons and connecting rods)
  • Cylinder heads
  • Assembly kit (gaskets, seals, etc.)
  • Tools
  • Performance engine assembly guide
  • Locate and purchase a serviceable GM aftermarket 502ci crate engine block (or core). While this block has a production cylinder diameter of 4.47-inches, the bore can be safely machined to the 540ci-required bore of 4.50-inches. Alternately, purchase an aftermarket block such as the Dart "Big M". This heavy-duty block is available in three bore sizes, including 4.50 inches, and can safely be machined overbore for subsequent rebuilds.

  • Purchase a rotating assembly (crank, pistons and rods) for the 540ci combination. Select component materials designed for the intended use. While cast components may be acceptable for standard-duty to slightly high-performance operation, cranks and rods made from forged 4340 steel and forged aluminum pistons are better able to withstand high-performance use. Many pre-configured kits are available, and some include piston rings, bearings, gaskets and seals.

  • Take the engine block and rotating assembly to a qualified engine machinist. Have the engine block machined and prepared ("blueprinted") to performance tolerances. This is critical. Areas to focus on are the main bearing journals, cylinder deck and cylinder bores, among others. The machinist will need the pistons in-hand for final cylinder bore fitting. It's recommended that the entire rotating assembly be checked for proper fit in areas such as rod and main journal measurements, connecting rod large- and small end bore sizes and piston-pin fit. Correct as needed.

  • Select cylinder heads, camshaft components and an intake system suitable for the intended application. While a standard-performance 540 could use factory GM cylinder heads, the airflow required by a 540ci engine will respond more favorably to a large-port design. Again, aftermarket vendors such as Dart, AFR and Racing Head Service, among others, offer several possible choices. For street-type high-performance, look toward heads with around 310- to 320cc of intake port volume. Racing applications can use larger-still heads.

    Select a camshaft that is properly suited for the head and intake system flow, and that is designed for the car and operating environment. This is also critical -- mis-matching camshaft/cylinder head combinations can result in much poorer performance that expected.

  • Carefully assemble the engine components according the the recommended procedures in the engine building guide. A very reasonable alternative is to have the engine machinist assemble the engine. Should there be any final fitment issues, he will have the tools at hand to immediately correct them. The time and expertise will likely justify the additional expense, as well.

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