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- 400 Engine Rebuilder Assemblies- Stock Stroke
400 Engine Rebuilder Assemblies- Stock Stroke
Pontiac V8 400 Engine Rebuilder Assemblies- Stock Stroke
Still a 400 When You Are Done — 400 Engine Rebuilder Assemblies- Stock Stroke for Pontiac V8s
400 Engine Rebuilder Assemblies keep the Pontiac 400 a 400. The stock 3.750" stroke stays, the block gets cleaned up, and new pistons, rings and bearings go in as a matched set. This is the shelf for a numbers-matching car, a driver that only needs to be right again, or a shop rebuilding a customer's 400 to better than new.
Butler covers it with re-ring kits, complete rebuild kits in cast hypereutectic or forged pistons, and balanced 406-413 ci rotating assemblies — including a build-your-own version for builders who assemble in house.
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More About 400 Engine Rebuilder Assemblies- Stock Stroke
1. Four ways to rebuild a 400
How far the engine came apart, and who is doing the assembly, decides which one you want.
| 400 Re-Ring Kit | Rings, rod bearings, main bearings and a complete engine gasket kit. The answer when the bores and pistons are still serviceable and the engine only needs freshening. |
| 400 Rebuild Kit, cast hypereutectic pistons | A complete kit of Butler-selected parts — pistons, rings, bearings and gaskets — for a stock-replacement rebuild that will live on pump gas. |
| 400 Rebuild Kit, forged pistons | The same idea with a forged piston, for a 400 that will see more than stock duty. |
| 406-413 ci balanced rotating assembly, 3.750" stroke | The full bottom end — crank, rods, pistons, pins, rings and bearings — matched and internally balanced in our shop. A build-your-own version of the same 3.750" package is available if you want the parts matched but the assembly done at your bench. |
2. Why the displacement is a range
A stock-stroke 400 is not one number. Bore options start at .030" over so the block cleans up and the rings seat within spec, and the finished displacement moves with that bore, which is why the assembly is listed at 406-413 ci rather than a flat 400.
| Measure before you order | Have the block checked and the final bore decided first. Larger bores are available if the cylinders need them. |
| Hone to the pistons | Butler recommends having the pistons in hand when the cylinders are honed, so piston-to-wall clearance is set off the parts that are actually going in. |
| Crank first | Main and rod bearings come in undersizes, so have the crank checked and turned before the bearing sizes are locked in. |
3. Rebuild now or leave room later
| A new cast steel crank | is an honest upgrade over a 30-plus-year-old factory crank and is recommended for street engines without power adders. Many factory cranks come in with stress cracks even when they have not let go yet. |
| A 4340 forged crank | costs more now and leaves the door open to add power later without pulling the engine apart a second time. |
| Balance hardware | A balanced assembly from our shop is internally balanced, so it needs a neutral-balanced flexplate or flywheel and a neutral harmonic balancer. |
If you already know the car is going to want more cubic inches eventually, look at the 400 stroker assemblies before you buy stock-stroke parts — the machine work overlaps, and doing it once is cheaper than doing it twice.
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.