Replacing your Mercury Marine 470 (3.7L)


Most marine engines are an adaptation of a automotive or truck block, not so for the Mercury 470. The 3.7L is an engine that was actually made by Mercury Marine. The block is aluminum with iron sleeves and it uses a Ford cylinder head. Freshwater cooling was standard. The alternator is built in to the harmonic balancer and the water pump is driven by the camshaft so no belts are used except for power steering.

It was sold with both a 2 bbl and 4 bbl carburetor with power ratings from 165 to 190 HP and last offered in 1989. This engine is no longer made as a complete package with the accessories, and even the remanufactured longblock is no longer available.

All models, regardless of the rated power or Mercury Marine designation used the same long block.

For a number of reasons we have found that sometimes it just makes more sense to replace this engine altogether. A new complete ready to install 3.0L  is a simple replacement for boats made after 1985. A complete 4.3 V6 is not much more and is a nice upgrade, however it is a little more work to install.

When the 3.7 was made, engine horsepower was rated using a very optimistic method. Power was measured at the flywheel under unrealistic and ideal conditions. Today a marine engine is rated at the propeller with all accessories in place under real-world conditions.

We have found that today's 3.0L (even though it is rated at 135 Propshaft horsepower) performs just about the same as the older 3.7L 2bbl versions. The new engine is actually smaller and mounts the same (off the front).

Please give us a call at 954 545 8681 with any questions.


New 3.0L (complete package is shown)