How to Build a 468 BB Chevy Engine

by Francis Walsh

The only reason to take a Chevrolet 454 cubic inch engine block and turn it into a 468 cubic inch engine is for pure speed or to use it in a race car. How you build a 468 BB Chevy engine depends on your preferences. Have it done for you or do it yourself with the help of these instructions. Be prepared to do some work yourself and leave the rest for the professionals if this will be your first attempt at building a bigger big block Chevy engine from a stock block with factory bore.

Secure a factory 454 motor on an engine stand to build a 468 BB Chevy engine. Disassemble the stock 454 big block engine. Remove the intake manifold, valve covers and timing gear cover. Remove the rocker arms and push rods. Pull the heads off of the block and remove the lifters.

Turn the engine over and remove the oil pan. Remove each piston by taking off the rod cap holding the piston to the crankshaft and pushing the piston out the top of the block. Take the timing chain off the engine block by loosening the three bolts holding the camshaft gear in place and then pulling the gear and the chain off the engine. Pull the crankshaft timing gear as well before removing the crankshaft from the block.

Remove the main bearing caps securing the crankshaft in place and pull the crankshaft out of the block. Store the crankshaft in a standing position. Clean the engine block to remove any corrosive materials on any surface, inside and out.

Machine the block to accommodate larger pistons. Hone the cylinder walls to 0.60 bigger than the original 454 bore so that a piston big enough to add 25.5 cc per cylinder can be fitted inside each cylinder. Machine the engine deck at the intake and heads to ensure a proper fit of these components now.

Put the block back onto the engine stand. Place the factory crankshaft into the main bearings and torque it in place with the main bearing cap bolts and a torque wrench. Lubricate every bearing during the install to prevent damage during the initial start up. Put the timing gear onto the end of the crankshaft.

Flip the engine over and insert the bigger pistons back into each cylinder using a piston ring compressor to squeeze the rings inside of the piston grooves while lightly tapping the piston down into each cylinder. Secure the piston rod to the crankshaft using a rod cap and two bolts. Grease every bearing surface, the cylinder walls and the sides of the pistons during installation.

Insert a camshaft into the engine. Secure the heads to the block using a gasket in between each head and the engine block. Insert the lifters and then secure rocker arms to each valve spring, which will hold a push rod in each lifter. Fasten a valve cover over each head. Install a cam shaft gear with timing chain over the crankshaft timing gear and cover them both with the timing chain cover. Attach the intake manifold and oil pan to finish the job.

Tip

  • check Oil and grease are critical here. Use more than you think you need and don't worry about the mess. Use rubber caps over the piston rod cap bolts to protect the crankshaft during installation of the pistons. Rubber hose works great. A large diameter hypodermic needle can work great at injecting oil over each journal before sitting the piston rod onto it.

Warning

  • close Friction kills a brand new motor in less time than it takes to blink during the initial start-up. Use plenty of assembly grease, plus 90- and 30-weight oil during the engine build of a 468 BB Chevy engine; it prevents "hot spotting" on the crankshaft, the camshaft and any of the bearings inside the engine block after assembly.

Items you will need

About the Author

Francis Walsh has been working as a freelance writer since 2003. He has contributed to websites such as Shave, Autogeek and Torque & Chromeas, as well as provided content for private clients. Walsh has worked as a performance part-packer and classic car show promoter, now serving as crew chief for Nitrousfitz Racing.

Photo Credits

  • photo_camera old car image by John Sfondilias from Fotolia.com