GM 4L85E AUTO 4-SPD

The ATK HP291PC is a 330 horsepower, 350 cubic inch complete crate engine designed for Chevrolet vehicles. It features an OE 4-bolt main block (1-piece seal, 1987-2000), a 4.040 x 3.480 bore/stroke, and a 9.1:1 compression ratio with hypereutectic pistons. The engine includes OE reground external/internal balance crankshaft, powder metal 5.7” rods, a hydraulic flat tappet camshaft (224/234 @50 .465in/.488ex 112LSA), double roller timing chain, and ATK cast iron cylinder heads (76cc/165cc 1.94/1.50). It comes with stamped steel 1.5 ratio rocker arms, a rear sump 5qt oil pan (with caveats for certain vehicle models), Melling high volume oil pump, 8” internal balance balancer, and a Pioneer #FRA-159 external balance 168 tooth flexplate. Fuel and ignition components include an ATK dual plane intake manifold, HEI distributor (iron gear), OE long water pump, Quick Fuel 670CFM vacuum secondary carburetor with electric choke, mechanical fuel pump, Champion #RV12C spark plugs, and 8mm spark plug wires.