ATK HP291PC Chevy 350 Complete Engine 330HP

ATK's HP291PC is the complete, ready-to-run version of its classic Chevy 350, rated at 330 hp and 380 lb-ft of torque on a flat-tappet cam that keeps the street manners of a factory-style small block.

What this tier adds

Unlike the base HP291P, the carburetor, balancer, distributor, water pump, and intake are all bolted on for this build rather than left as recommendations, and the flexplate or flywheel ships too. The same factory-style cast-iron heads and 9.1:1-compression hypereutectic pistons carry over from the base engine.

A few things worth confirming

• Dipstick placement follows the rest of this family: passenger side of the vehicle.
• ATK's fuel pump here is a mechanical type, matched to the installed carburetor.
• Give it roughly 3,000 break-in miles on conventional oil with a zinc additive before switching to your normal routine.

Common questions

Is the carburetor already mounted? Yes, the vacuum-secondary, electric-choke carburetor ships already bolted to this complete engine.

Will it still run vacuum-powered brakes? Yes, the flat-tappet cam used here keeps enough vacuum signal for power accessories.

What's the torque rating? 380 lb-ft, paired with 330 hp.

What's different from the base HP291P? This complete version has the carburetor, balancer, distributor, water pump, and intake bolted on; the base engine leaves all of that for the installer. California requires BAR compliance for engine swap installations.