This is a replacement engine for a Mercruiser 450hp 502ci marine engine.

Engine Specifications

• Horsepower: 515 hp
• Torque: 570 lb/ft

Block Information:

• Dart Big M 4-bolt main 1-piece rear main seal
• Bore/Stroke: 4.470" x 4.000"
• Displacement: 502ci

Rotating Assembly:

• Crankshaft: Scat nodular iron 
• Balance: External
• Rods: Scat 4340 I Beam 6.385" with ARP 8740 bolts
• Compression Ratio: 8.9:1
• Pistons: Forged
• Rings: Moly

Camshaft Specs:

• Camshaft: Hydraulic roller
• Cam Duration @ .050": Intake 224 / Exhaust 224
• Cam Lift: Intake .483" / Exhaust .483"
• Lobe Separation Angle: 112lsa
• Timing Chain: Single roller

Cylinder Head Information:

• Cylinder Heads: Dart Iron Eagle
• Combustion Chamber: 119cc
• Intake Runner: 308cc
• Valve Size: 2.250" Intake / 1.880" Exhaust
• Rocker Arms: Stamped steel 1.7 ratio

 Engine Info

• Firing Order: 18436572
• Octane: 91+
• Oil: 10W30 (Conventional / Non Synthetic) 
• Oil Filter: Wix or K&N
• Spark Plug Gap: .035"
• Timing: 34-36 Degrees 

Recommended Components

• Balancer: External balance
• Fuel System: Factory EFI or Quick Fuel Marine 750cfm #793-M-750 carburetor 
• Distributor: Factory or aftermarket marine grade
• Intake Manifold: Factory EFI or aftermarket dual plane
• Fuel Pump: Factory or mechanical 110gph
• Spark Plugs: Autotile #417-3933
• Spark Plug Wires: Marine grade 8mm
• Water Pump: Factory 

 Disclaimer: The parts listed are ATK's recommendations of parts to be used to obtain the power figures listed. Power figures can vary based on parts used by the end user. Some modifications to the vehicle may be required using these and or other aftermarket parts.

Engine Break-In Procedure

Use or break-in oil or conventional (non-synthetic) 10w30 oil with zinc additive for the first 500 miles of operation.  Do not drive for long periods at any single speed, always vary your speed. Do not tow a trailer or put other heavy loads on the vehicle. It is best to avoid long periods of idling during this period. Check the engine oil and coolant levels daily. 

Engines with flat tappet hydraulic cams only - Run the engine between 2,000 and 2,500 RPM's, with no-load on the engine for the first 30 minutes. Let the engine cool down completely and repeat process 2-3 more times. Do not idle the engine for any extended period at this time, this is critical to break in the camshaft.

At 500 Miles change the engine oil and filter using conventional (non-synthetic) oil with a zinc additive. Check fuel and ignition settings, adjust valves (where applicable).  Drive the next 500 miles normally, without high RPM's (below 5000 RPM), hard use, or extended periods of high loading or long periods of idling.

Change the oil and oil filter again at 1,000 miles. Continue using conventional (non-synthetic) oils and zinc additive, until about 4,000 miles. At that point, you may run a quality 10w30 synthetic oil if you choose. Use of oil with zinc or a zinc additive for the life of your engine is recommended. 

Please CLICK HERE for ATK Warranty