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- 350 Block
350 Block
Pontiac V8 350 Block
Small Bore, Long Legs — 350 Block for Pontiac V8s
The Pontiac 350 is the light end of the 3.00" main family, and it is the casting people reach for when the car came with one and they want it to keep its identity. Stroked properly it stops being the slow block in the lineup and starts being a quick-revving street engine.
These are Short Block Kits (SBK) on a Butler supplied 350 block: prepped block plus a balanced rotating assembly with a cast or forged crank, Ross custom pistons, Total Seal file fit rings and performance rod and main bearings. No camshaft, no cylinder heads, shipped ready to assemble.
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More About 350 Block
1. The three stroke choices
The 350 block takes the same stroker cranks the bigger castings use, so the displacement gap closes fast. Each kit pairs a stroke with the correct rod.
| 3.750" stroke | cast or forged crank on 6.625" I-beam rods, supplied press fit and not assembled. This is the budget-friendly end of the 350 range. |
| 4.000" stroke | forged crank on 6.700" H-beam rods. The middle option and the one most 350 owners are actually after. |
| 4.250" stroke | cast or forged crank on 6.800" rods. The most stroke Butler builds into a 350 block. |
2. Bore and pistons
Bore is where the 350 differs most from the rest of the Pontiac V8 line, and it is worth knowing before you plan compression.
| Available bores | 3.905" and 3.935". These kits are built to one of those two, so your piston, ring and final displacement all follow from that choice. |
| Ross custom pistons | pistons are made for the combination rather than pulled off a shelf, which is what makes an odd bore and a long stroke work together. |
| Total Seal file fit rings | gapped to your bore and your intended use during assembly. |
| Internally balanced | the assembly is balanced as a set, so the damper and the flywheel or flexplate you buy must be neutral balance parts. |
3. Block prep and what comes next
Every 350 block in these kits is cleaned, magnafluxed, sonic tested, completely deburred, bored and honed with a torque plate, line honed with ARP main studs and square decked, with cam bearings and brass freeze plugs installed before it is boxed.
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.