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Pistons
Pontiac V8 Pistons
Compression Starts Here — Pistons for Pontiac V8s
Pistons set the compression ratio, and compression ratio decides what fuel your Pontiac V8 will live on. Everything else in the bottom end can be right and the wrong piston will still hand you detonation on pump gas or a lazy engine that never makes what it should.
Butler organises pistons by block — 326, 350, 389, 400, 421, 428, 455, plus aftermarket block sets — and stocks Ross Racing, DSS Racing, Icon, Keith Black and Federal Mogul, in cast hypereutectic and forged, flat top, dish and dome.
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More About Pistons
1. Start with the block, then the bore
The pages under this category are split by engine for a reason: bore size and pin height change with the block, and a 455 piston has nothing to do with a 350.
| Pick your displacement page | 326, 350, 389, 400, 421, 428 and 455 each have their own listing, along with a page for aftermarket-block pistons. |
| Then the finished bore | Sets are catalogued standard and over — commonly .030", .040" and .060" — and on the custom pistons by the exact finished bore. Order to what the block actually measures after honing, not to what you intend to cut. |
| Then the stroke | A stroker crank changes the compression height the piston has to have. Crank, rod and piston are one order. |
2. Cast hypereutectic or forged
Both are legitimate. They belong in different engines.
| Hypereutectic cast | Keith Black's high-silicon alloy pistons run tight and quiet and handle street and mild-performance use at lower cost than forged. This is the stock-to-street rebuild answer. |
| Forged | Ross, DSS and Icon all forge in 2618 alloy here. This is what goes in a stroker, a high-rpm engine, or anything with a power adder behind it. |
| Ring gap is not the same | Keith Black states its hypereutectic pistons require a much wider top ring end gap than traditional forged pistons. Do not carry a forged gap spec over to a KB piston. |
3. Crown shape, chamber volume and heads
This is the part most people get wrong, and it is the part that decides whether the engine runs on pump gas.
| Dish, flat, dome | Butler stocks all three across the displacement pages. The right one depends entirely on your cylinder head chamber volume and your stroke. |
| Head compatibility | Several piston families here are listed for specific heads — some for OE or Edelbrock style chambers, some for 14-degree or 20-degree heads, some for 1964-66 22-degree heads only. That note on the product is not a suggestion. |
| Custom sets | Ross and DSS both offer fully custom pistons where you specify bore, stroke and crown. That is the route when an off-the-shelf set will not land on your target compression. |
If you tell us the block, the finished bore, the crank stroke and the chamber cc of the heads, the piston picks itself. Every rotating assembly Butler sells gets weighed, pin fitted and balanced in house before it ships.
455 Pistons 389 Pistons 400 Pistons 421 Pistons 428 Pistons
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.