Replacing the Mercruiser 470 (3.7L) Engine - Performance Product Technologies

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Dennis, Thanks for your inquiry and the opportunity at earning your business. Since Mercruiser made both Alpha and Bravo sterndrive models with that engine I would not be able to tell you without knowing which one your engine is setup for. Can you give me the original engine serial number? Or can you tell me if [...]

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Marty, Thanks for your inquiry and the opportunity at earning your business. Using the links below you can review your options. Let me know if you need any further technical information or help placing your order. In either case I will be glad to assist! Link to Block Code/Serial Number Location http://www.perfprotech.com/store/app_themes/PPT/images/block-casting-no.jpg Link to Remanufactured Longblocks http://tinyurl.com/68kcet8 Link to Remanufacturing [...]

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Question: What's the best direction to go when replacing the old Mercruiser 3.7L/470 engine?

Unfortunately there is no single good option for this looking at a complete re-power. The 470 engine was an engine developed by Mercury Marine specifically for it's purpose; to power boats. The inline configuration allowed for easy draining, a single intake/exhaust manifold was cheaper than two, etc. The engine was also a large displacement engine for its size and therefore made a tremendous amount of torque because of the stroke and displacement. On top of this Mercury utilized their die casting expertise to produce a light weight aluminum block and combination with the existing Ford cast iron 460 cylinder head.

To go up in Hp you will have to go with the typical V-Configured 350 engine which will also require a different drive ratio and propeller. With any changeover to the V engine configuration be it V6 or V8 this will also require completely rebuilding the stringer system in your boat. Many customers ask about replacing the 470 engine with the current 3.0L engine since they are also are an inline configuration. The problem with this is that the 3.0L makes approximately 135 Hp & 180 Lb-Ft of torque where the 470 made 190 Hp and approximately 275 Lb-Ft of torque. The 3.0L engine is simply too small and does not make enough torque.

Therefore the prevailing direction for 99% of boat owners in this position is to go with the remanufactured 470 longblock. The remanufactured longblocks are of a very good quality and have a 24 month warranty. This is important versus rebuilding realizing this was not a standard automotive product and therefore most local rebuild shops do not have the experience to produce a comparable, good quality product.

Installation Drawings for reviewing specific dimensional differences (open is separate windows)

470 (1976 Model) Installation Drawing (Select Link)

470 (1978 Model) Installation Drawing (Select Link)

3.0L (Inline 4 Cylinder) Installation Drawing (Select Link)

4.3L (V6) Installation Drawing (Select Link)

5.7L (V8) Installation Drawing (Select Link)

Tech Tips (Select Link)

Remanufactured Longblock Product (Select Link )

Technical Articles

Question: What's the best direction to go when replacing the old Mercruiser 3.7L/470 engine?