Originally published in the September 1964 issue of Hot Rod Magazine. Article & photos by Eric Rickman
Although the versatile little Corvair engine has appeared in almost every guise the hot rodder could conceive, it remained for Bob Laughton of Monza Enterprises in Sherman Oaks, California, to come up with this most unique application. Bob’s shop specializes in Corvair maintenance and, during moment of contemplation on a tired Merc outboard in need of overhaul, he came up with the idea of substituting the air-cooled Chevy mill in place of the marine unit.
Here’s what had to be done.
Adapter plates were machined and a driveshaft made up to join the rear of the Corvair crank to the Merc prop shaft. With the engine standing on end, a new carbureation system had to be found; Bob remembered seeing Del Orto cycle carbs used on an engine of this sort in HRM and set up some 7/8-inch Venturi jobs on a mounting plate of his own design. The throttle sides are controlled by a Marbet hydraulic actuator.
The innards of the present engine are stock but this setup peaks out too quickly at just over five grand with the steepest pitch screw, so Iskenderian was contacted and he is providing a new high-rev hydraulic lifter cam which should extend to the RPM range to 7,500. The stock thrust bearing carries the weight of the crank in the vertical position; if additional thrust bearing surface is needed, another bearing will be installed on an adjoining web. With the engine standing on end, a new oiling system had to be devised. The crankcase is now of the dry sump type and the rocker boxes are connected to a new sump with aircraft braided hose to provide drain back. 6 1/2 quarts of oil are carried below the waterline in the Merc 700 lower end. A scavenging pump picks up the oil from the sump and feeds it to the engine’s pressure pump. Bob put the hollow space ub the lower end unit to use; it increases oil capacity and acts as an oil cooler.
Another little project, the starter system, really called for ingenuity. Not wanting to retain the heavy starter and flywheel of the automotive engine, Bob built a command roller type of overriding clutch which he incorporated into the hub of a large sprocket mounted on the front (top) of the engine. Two small Honda 6-volt starters were mounted on the engine and the three units then connected with motorcycle roller chain. With 12-volts energizing the 6-volt starters, the engine cranks over merrily.
Why go to all this trouble?
Just think about it… a Corvair is a relatively low rpm, good torque engine with 144 cubes – plenty of power with low gas consumption. The big outboards are only 44lbs lighter, and the hop-up potential of the Corvair is almost unlimited. The Corvair gets power at a much lower rpm which makes picking up a skier, for example, much easier. Fuel consumption, too, should be considerably improved, and this is a big consideration with Bob as he is contemplating both the drags and endurance runs such as the coming Salton 500.
This way-out outboard should be able to cruise all day between 5-6000 rpm with horsepower at 145-150 after the Isky camis installed to bring the revs up. We’ll keep you posted on this project.
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