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389 Super Stroker Rotating Assemblies- Up to 4.500 Stroke
Pontiac V8 389 Super Stroker Rotating Assemblies- Up to 4.500 Stroke
The Last Step on a 389 — 389 Super Stroker Rotating Assemblies- Up to 4.500 Stroke for Pontiac V8s
Super stroker is Butler's name for the longest crank a given block will take, and on a 389 that means a 4.500" stroke. It is the last step available on this block before an aftermarket casting, and it produces displacement a 389 was never sold with.
Butler's 389 super stroker rotating assembly is a balanced 473-480 ci package on a 4.500" stroke, built around Ross forged pistons on the Butler true-Pontiac forging and internally balanced in our shop like every assembly we sell.
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1. What the 4.500" assembly is
This page holds one combination, and it is the top of the 389 range.
| 473-480 ci on a 4.500" stroke | Butler's balanced long-rod stroker assembly for the 389 block. The displacement lands where it lands according to the bore your block cleans up at, which is why it is quoted as a range rather than a single number. |
| Built like the rest of the line | Genuine Ross forged pistons on Butler's exclusive true-Pontiac forging, Total Seal rings, performance bearings and the Butler Process internal balance, with rods and pistons weighed and pin-fitted and the crank computer balanced to the assembly. |
2. What a super stroker asks of the block
A 4.500" crank is a serious amount of stroke in a factory casting, and the block has a vote.
| Casting number matters | Butler does not recommend long-stroke combinations in blocks with casting numbers ending in 557 — those have thinner main webbing, and we suggest holding them to 4.000" stroke and under 500 hp. Identify the casting before you order. |
| Clearancing | Long-stroke Pontiac combinations need the block checked for rod and counterweight clearance. Have your machinist mock it up rather than assume it drops in. |
| Neutral balance hardware | Internally balanced means a neutral flexplate or flywheel and a neutral harmonic balancer. Order them with the assembly. |
3. Getting the compression right
| Tell us the heads | Chamber cc and your fuel decide the piston. Our techs work with Ross to design a flat top or custom dish that hits the compression ratio you ask for. |
| Plan the calendar | Custom dish pistons run a 10 to 12 week lead time, so the piston order usually needs to go in before the block is finished, not after. |
This is the point where the rest of the combination has to keep up — heads, cam and induction all become the limit once the displacement is there. Call before you order and we will make sure the top end matches what the bottom end can do.
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.