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Dave Petersen, Tucson, AZ.    (          1/22/2011


This verticle single OHC model was started Nov. 19th, 2010 and first run Dec. 27th, 2010.  It is my second I/C and a first scratch built concept.  The 7/8th. inch bore with 1 1/8th inch stroke (11CC's) DOM cylinder sits atop a frame of 2x2 and 2x3 aluminum angle. The Sentinel features inboard points ignition, 1.5 lbs. brass flywheel, overhang crankshaft, single overhead camshaft. A couple of details on the engine are a three piece connecting rod. Big and small ends and the beam. This allows for a change in compression by adding/ removing flat washers from the small end of beam. The cam drive is not slotted to change valve timing. The cam lobes are made with a hub and are tied to its shaft by a set screw and can be timed like a DOHC engine as the intake and exhaust lobes are independent of each other.  The drive is "MXL" cogs with a  .250in. belt.  An on deck copper plumbing fuel tank feeds a small non-throttling R/C carb for 20 minute run times and a 2 inch fan pulls air into the radiator.  The points set is Tecumseh small engine, note the half the size of automotive condenser here.         



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