ATK Engines ATK 13ZB 350 SBC Bare Block Machined/Ready To Assemble

ATK's 13ZB is a 100% new bare 350 Small Block Chevy block, cast and machined rather than reworked from an old core, and sold ready to assemble rather than as a running engine. It comes with the camshaft bearings and brass freeze plugs already installed, and is stroker clearanced for builders planning a longer-stroke rotating assembly. What's already done for you The block is bored to a 4.000" standard size (machined within 4.0003-4.0008") with a 4.060" maximum recommended bore, uses a premium iron alloy casting based on the Vortec 350 roller block pattern, and keeps a standard deck height with a 9.014" minimum deck. ATK sets it up with a 4-bolt main, cast iron main caps and fasteners already in place, a priority main oiling system, and a fuel pump boss, and the block is roller camshaft compatible. What you still need to add Main bearings are not included, so budget for those along with the rest of your rotating assembly, heads, and accessories separately. Because bore sizes vary slightly within ATK's machining tolerance, final honing may still be needed to match your pistons. This bare block is an engine-change part, not a direct OEM swap, and California requires BAR approval for that kind of engine change. Common questions Does this block come with main bearings? No, main bearings are not included; cam bearings and freeze plugs are. Can I run a roller cam in this block? Yes, ATK lists it as roller camshaft compatible. What's the standard bore? 4.000", machined within 4.0003-4.0008", with a 4.060" maximum recommended bore.