How to Put a Chevy 396 Crank Shaft in a Chevy 454

Updating the crankshaft and pistons in a Chevy engine requires planning and a degree of mechanical skill.

Versatility is the primary reason that the Chevy big block engine remains one of the predominant power plants in hot rodding, decades after the first 454 engine block was cast. With Mopar and Ford engines, swapping parts between types of engines is often impossible, and in the few instances that it is possible, the swap requires a high level of pain-staking modification and fabrication to make work. With the Chevy big block, though, most parts are in fact compatible, giving muscle car enthusiasts plenty of options to work with. Installing the crankshaft of a 396 into a 454 requires a few different parts, but it is a straightforward task.

Things You'll Need

• Connecting rods and pistons for a 427 Chevy big block
• Flywheel for a 396 crankshaft
• Internal harmonic balancer
• Standard socket set w/ratchet
• Torque wrench

Instructions

The Installation

1. Place the 396 crankshaft into the main bearing journals of the 454. Turn the crankshaft for a couple of revolutions to ensure that it does not bind or score the journals at all. Attach the main bearing caps and tighten to specifications, 70 ft-lbs of torque.

2. Place piston rings onto the new set of 427 pistons and attach the connecting rods. You must use 427 pistons and rods because the 396 crankshaft alters the rotational radius of the crankshaft. This, in turn, alters the total displacement of the 454 engine block, making it a 427 engine.

3. Slide each piston downward through the breach of the corresponding cylinder. Connect each rod to the crankshaft and torque it per the manufacturer's recommended specifications. Attach the oil pump the assembly located near the pinion gear for the distributor shaft.

4. Attach the internal balancer to the crankshaft. Affix the flywheel to the output shaft of the crank. Rotate the engine so that the front left cylinder is at the height of its travel (top dead center).

5. Place oil pan with a new gasket onto the bottom of the engine.

Tips & Warnings

• Have your 454 block inspected by a machine shop prior to assembly. Also, have that machine shop check the usability for your 396 crankshaft; it may not ultimately be usable.

• Do not attempt to use the pistons and connecting rods for a 454. The 396 crankshaft will not be able to accommodate them, as they cannot handle a full four-inch stroke.

References

• Chevy High Performance: 454 Big Block Project

Resources

• Super Chevy Magazine: Chevrolet 396 Big Block Build