9. What is the difference between an Atomic 4 and a Stevedore Atomic 4?

The Stevedore is the name of the Atomic 4's which were shipped into Canada. They are exactly the same as the "regular" Atomic 4, except for a small restrictor ring that was inserted into the inlet of the intake manifold, just above the carburetor mounting flange.

The reason for the restrictor ring was to limit the maximum HP of the engine, so as to comply with Canadian laws regarding the amount of HP (28 - or so) that could be used in sail boats in the 30-foot class. I don't know what the current situation is with respect to Canadian laws governing the amount of power that can be used in which size of sailboat, but by this time, most of these restrictor rings have been removed from any Stevedore that has found its way back into the US.

In the event that you find this round restrictor ring in the mouth of your intake manifold, you can work it out with a large screwdriver and discard it.

After you remove a Stevedore restrictor, you may or may not notice any difference in performance. The power limitation was most apparent at the very high end of the RPM range of the engine. At RPM below approximately 2500, the restrictor had a minimal effect. - Updated: December 3, 2003