Which One Has The Rotary Valved Fully Bearing Supported Crank?

[John (Taylor) Gabrowski]

Just before the Swamp Pit message board was blasted out of service to racers, a discussion came up about "fully supported" crankshafts and "rotary valve crankshafts" for Mercury 4 cylinder use, specifically for Alky Deflector engines with Quincy compression padded and piped. Out of Iowa came discussion posters that told the stories of how some of their racing members made up these strange and different crankshafts in the little machine shops and backrooms they did them in. There were about 3 posters who saw they made, helped make them and saw them run. There were about half a dozen crankshaft variants built. I had 2 of these variants myself for a time and even tried one, the one with Hot Rot like rotary valves where the reed blocks would have been and the crank altered to "chop in and compress the air/fuel intake". That crank weighed 1/3 more than a conventional Mercury crankshaft for a 55H. The other crankshaft not only has the rotary valve but also has roller bearing support like a Merc 20H with the crankcase section of what would have been the reed block but is the rotart valve half the crankshaft side works with. Thhe following engines pictures is a Mercury Mark 30H Modified, A Merc Mark 55H Modified and the last is a Mercury later model Merc 500 Anniversary Special 44 cube engine. Which one has that crazy crankshaft that fits like hand and glove is your readers guess?? Was that crankshaft any better is unknown but the other one without the extra bearing support and 1/3 rd heavier running methanol with single ring Turners in a padded block Mark 55H-1 was impressive for torque at the high end but otherwise a very hard on or less than 3/4 throttle off type engine.

Enjoy the pictures. May very well turn up at Wakefield APBA Nats but not sure quite yet.