ATK SP35NB 100% New Chevy 377 Stroker Forged 16cc Dished Pistons

Builders who already own a set of heads and just need fresh internals underneath them are the target for the SP35NB, a 100% new short block for Chevy 377 stroker combinations. ATK supplies the block itself as new production, not a core rebuild, fitted with a Scat crank kit and a one-piece rear seal, ready for your own top end.

Why a short block instead of a long block

Nothing above the deck ships here: no cylinder heads, intake, carburetor, distributor, valve covers, or accessories. That keeps the price down for anyone who has usable heads sitting on a shelf, or who wants to pick a specific head casting rather than take whatever a long block includes.

What is actually inside

A forged Scat 4340 crankshaft and matching forged H-beam connecting rods, secured with ARP bolts, ride on forged 2618 pistons carrying a 16cc dish and two valve reliefs. The 377 cubic inches come from a 4.000-inch bore and a 3.750-inch stroke. Plasma-moly rings, Dura-Bond cam bearings clocked to the OEM position, and brass freeze plugs are installed and sealed before it leaves the factory, and the flexplate or flywheel side uses external balance with a 168-tooth ring to match the Scat kit.

Q: What compression should I expect? Roughly 9.2:1 to 10.4:1, depending on the chamber size of the heads you bolt on; this short block does not fix that number for you.