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Rings
Pontiac V8 Rings
Sealed to the Bore — Rings for Pontiac V8s
Piston rings are the last thing bought and the first thing blamed. They seal combustion pressure, control oil, and carry heat out of the piston into the cylinder wall — and they are sized to the finished bore of your block, not to the engine's badge.
Butler splits rings by block — 326, 350, 389, 400/428, 421, 455 and aftermarket — and stocks Total Seal Classic Race sets in file fit and drop in, plus Sealed Power stock-thickness sets in the factory overbore steps for a straightforward rebuild.
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1. Order to the measured bore
Ring sets are catalogued by bore diameter, and the Pontiac bore list is long. Guessing costs you a set.
| The stock steps | Sealed Power catalogues the 350 at 3.875" standard, 3.905" at .030" over, 3.915" at .040" and 3.935" at .060". Every displacement page here works the same way — a standard bore and the common overbore steps. |
| Stroker and aftermarket bores | The larger bores Butler stocks rings for run well past the factory sizes, including 4.310", 4.350" and 4.375" on the aftermarket block page. |
| Measure after honing | A block honed to a specific size needs a ring cut for that size. Order after the machine work, not before. |
2. File fit or drop in
Total Seal's Classic Race sets come both ways and the difference is real work on the bench.
| File fit | Supplied oversize so you set the end gap yourself — a 3.905" bore set ships as a 3.910" ring, a 4.120" bore set as a 4.125" ring. This is the route for a performance engine where the gap has to be right for the application. |
| Drop in | Pre-gapped for the listed bore. Faster, and appropriate on a straightforward rebuild. |
| Stock thickness | Sealed Power's sets are the conventional stock-thickness answer for a factory-spec rebuild. |
3. Match the ring to the piston, not just the bore
The piston dictates the ring package, and this is where builders get caught.
| Groove sizes differ | Forged Pontiac piston sets here commonly call for a 1/16", 1/16", 3/16" package, while hypereutectic cast sets often call for 5/64", 1/16", 3/16". Read the piston, then order the ring. |
| Cast pistons want more gap | Keith Black states its hypereutectic pistons require a much wider top ring end gap than traditional forged pistons — .0065" per inch of bore for a street engine. Do not apply a forged spec to a cast piston. |
| Gas ported pistons | Where a piston is gas ported, the rings and gaps have to suit the porting. Call before ordering on those combinations. |
Bring the finished bore and the piston part number. Those two things answer this page, and they are the two things nobody has written down when they call.
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.