BluePrint MBP3830CTC GM 383 Base Marine Engine, Cast Iron Vortec Heads

Moving up in displacement from BluePrint's other marine long blocks, the MBP3830CTC is a new 383 cubic inch GM engine with cast iron Vortec heads and a roller camshaft, rated at 405 HP and 450 ft-lbs of torque at 9.5:1 compression. The rotating assembly is internally balanced around a new cast steel premium crankshaft.

Why the roller cam matters

Unlike flat-tappet marine engines, this one runs a roller cam with 220 degrees of intake duration and 224 degrees of exhaust duration, paired with 1.940-inch swirl-polished intake valves and 1.500-inch swirl-polished exhaust valves. Bore and stroke land at 4.040 inches by 3.750 inches, with the block sonic tested and align honed for wall thickness and bearing bore accuracy.

What ships bolted on

• A 750 cfm carburetor and distributor, ready to fire once fuel and electrical are connected
• Polished aluminum valve covers paired with a cast iron circulating pump
• Ignition hardware: a harmonic balancer plus spark plugs and BluePrint wires
• Fuel pump, fuel line, and filter, plus the new cast iron marine intake

Dyno results ship with every engine. Recommended oil is 10W30, non-synthetic, and this build is not intended for EGR applications.

Emissions note and coverage

Buyers planning to swap this engine into a California-titled vehicle should expect it to fall under the state's engine-change rules rather than treating it as a direct OEM replacement. Warranty is 12 months, unlimited hours, for pleasurecraft use only, with no coverage for commercial use. Part number MBP3830CTC.