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Aftermarket Block
Pontiac V8 Aftermarket Block
Past the Factory Casting — Aftermarket Block for Pontiac V8s
There is a point where a factory Pontiac casting runs out of cylinder wall and main web, and the honest answer is a new block. The IAII aftermarket block is where Butler goes for 505 to 541 cubic inches — more bore, more stroke clearance and a bottom end designed for it from the start.
This is a Short Block Kit (SBK) on a new IAII block: machined and prepped, with a new 3.00" main crank, Ross pistons, H-beam rods, file fit rings and FM or Clevite racing bearings, balanced internally. No camshaft, no heads, shipped ready to assemble.
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1. Why the IAII block
The IAII is a purpose-built Pontiac block, and the differences are structural rather than cosmetic.
| Siamese cylinders | the aluminum block is cast at 4.170" and can be bored to 4.350", which is bore no factory casting will give you. |
| Stroke clearance | the casting clears a 4.750" stroke crank, and the bottoms of the cylinders are notched for it. |
| Main caps | all-steel registered caps with a splayed four-bolt pattern on the three center mains, included with the block along with main studs. |
| Street or race | the aluminum IAII is fully water jacketed, so it is not limited to a race-only application. |
2. What is in the kit
The parts list is specified around the block rather than adapted to it.
| Block | new IAII, sonic tested, completely deburred, bored and honed with a torque plate, line honed, deck squared, with cam bearings and brass freeze plugs installed and ready to assemble. |
| Crank | new, 3.00" mains, 4.250" or 4.500" stroke. Forged as standard, with a billet crank available. |
| Rods and pins | H-beam rods with optional ARP 2000 bolts, pin fitted. |
| Pistons and rings | Ross pistons to the bore you choose, with file fit rings. |
| Bearings and balance | Clevite or Federal Mogul racing rod and main bearings, balanced internally. |
3. Specify it carefully
Two things catch people on an aftermarket block build. First, machining and bearings for a 50mm or 55mm cam are not part of the base kit, so if a large cam tunnel is in the plan it has to be specified. Second, this is still a short block — there is no camshaft and there are no heads.
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.