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455 Block
Pontiac V8 455 Block
Start Big, Finish Bigger — 455 Block for Pontiac V8s
The 455 starts with more cubic inches than any other factory Pontiac block, so an assembled 455 short block is the shortest route to a genuinely big-inch Pontiac. It ships as a finished bottom end: machined 455 block, crank, H-beam rods, pistons, rings and bearings installed and internally balanced.
Butler builds it as a Custom Short Block in three strokes, covering 462-469 through 494-501 cu. in., with a cast or forged crank, Ross pistons in flat top, dish or dome, file-fit rings and a Viton rear main seal, assembled by a Butler engine specialist and shipped on a reusable cradle.
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More About 455 Block
1. What the 455 Brings to the Table
The 455 already has the bore and the 3.25" mains, so every inch of stroke you add lands on top of a large baseline instead of digging you out of one.
| Bore range | Butler's 455 stroker assemblies work in the 4.181" to 4.211" range, which is where the block cleans up and the rings still have wall to seat against. |
| Large main journals | 3.25" mains mean 421/428/455 crank and bearing parts, and the large-main one-piece Viton rear main seal. |
| Torque first | this is a street and muscle-car block. Even the shortest stroke Butler offers here lands in the 460s, which is where a 455 car feels like a 455. |
2. Three Strokes, and What Each One Is For
Choose by intent, not by the biggest number. The stroke sets the rod length, the piston and how hard the main webbing works.
| 4.210" stroke, 462-469 cu. in. | the conservative stroker. Good manners, easy parts availability, and no special main cap requirement. |
| 4.250" stroke, 467-474 cu. in. | Butler's most-built 455 combination, and the one the 6.800" long-rod parts are designed around. |
| 4.500" stroke, 494-501 cu. in. | five hundred inches out of a factory casting. Butler recommends 4-bolt billet main caps at this stroke. |
3. Specifying It Correctly
Two pieces of information from you decide most of the build, and both are easy to get before you order.
| Cylinder head chamber | add your head casting or chamber cc at checkout. Butler confirms the compression ratio and then orders the piston to suit, flat top, dish or dome. |
| Balance | these assemblies are internally balanced, so the back of the engine needs a neutral-balance flexplate or flywheel rather than a factory externally balanced piece. |
| Block prep included | cleaned, magnafluxed, sonic tested, deburred, bored and honed with a torque plate, line honed with ARP main studs, deck squared, cam bearings and brass freeze plugs installed. |
A 455 short block leaves you the cam, heads, intake and oiling to buy. Those four decide whether the cubic inches show up as street torque or as a dyno number, so pick them as one package rather than one at a time.
Not sure what your Pontiac needs?
Call our tech team at 866-762-7527. Tell us your engine, heads, car, and power goal, and we will put the parts together as one combination that works.