The 401 was built to produce 425 hp but with a broad torque range that extends well into the higher rpm. Machining was done by Phil’s Machine Shop in Danville, Illinois. The block was bored 0.040 over and given TRW piston with a 10.5:1 compression ratio. It uses massaged factory dogleg-port AMC heads with valves that are popped by a Comp Cams Magnum 280H cam via Comp Cams roller rockers. A Quick Fuel four-barrel supplies fuel through an Edelbrock Airgap intake manifold. An MSD distributor makes the fire, and the truck uses a dual ignition system to make sure heat, water, or dirt doesn’t stop the truck. The well-used exhaust exits through headers built by John Conrad at JB’s 4x4 and through a custom dual exhaust system. The engine mounts a compressor and a Premier Power Welder.