Overhead Valve Engines

VA


The Lauson Model Type VA of 1929 is a cast iron, single cylinder, vertical cylinder, F-head, open rocker engine stated to develop 1 ½ HP at 1200 RPM and 2 HP at 1800 RPM; it has a bore and stroke of 2 ¾ in. by 3 ¼ in. It is a fairly sizeable engine (by small engine standards) standing approximately 21 inches tall and weighing around 95 lbs. They were built as rope start or crank start.

The VA has an exposed flywheel with internal air vanes that draw air down through the cylinder head cover and past the vertical cast iron cylinder cooling vanes, down through the cast aluminum air duct attached to the side of the engine, and then out through the fan blades within the flywheel. The engine was built with an external magneto, a Wico B1 is the standard magneto for this engine. The engine is equipped with an external casting that encases a flyweight governor to control the throttle of the Tillotson MS-22C carburetor. The magneto and governor are driven by the camshaft, which is lubricated through the crankcase oil system on one end and an external oil vent on the other. Of course, the two-lobe camshaft also drives the lifters and pushrods to operate the exposed rockers and overhead valves. The crankshaft is supported by tapered roller bearings and it has bolt-on counter-weights that must be removed in order to facilitate its removal. The steel piston has three piston rings. The engine is equipped with an oil pump, actuated by a pushrod that rides an eccentric on the camshaft via a ½ circumference eccentric strap. The oil pump delivers oil into a wide trough under the crankshaft where the crankshaft counterweights splash the oil about the crankcase for lubrication (there is no dipper). The engine has an oil level indication system, comprised of a cork float mounted to a lever in the oil sump. This lever rotates a shaft protruding through the crankcase, and that shaft positions an oil level pointer that indicates the crankcase oil level on a scale attached to the outside of the engine block. The connecting rod is interchangeable with a model "T" connecting rod.

The Model VA was built into the late 1930's.

The engine pictured is from my personal collection. You may view other pictures of it by clicking Here

VR


The VR is a water cooled version of the VA, equipped with a radiator.

VW


The VW is a water cooled version of the VA, equipped with a cooling tank. Many VW were sold under the “Alpha DeLaval” label, and were used to drive milking machine equipment. Water that the engine heated was collected in the attached tank and used to sterilize the milking equipment when the milking was concluded.

The supplied picture is from the collection of Harry Mathews.
The Photos are from the collection of Ron Little

UA


The UA is an upgraded VA with a different cylinder head and carburetor. These changes gave the engine and additional HP over the VA.

The UA was built from around 1933 through till the end of the 1930's.

UR


The UR is an upgraded VR with a different cylinder head and carburetor. These changes gave the engine and additional HP over the VR.

The UR was built from around 1933 through to till around 1940.

UAS


1933 saw the production of the model type UAS. The UAS is an upgraded VA, producing 3 HP at 1750 RPM and 4 ¼ HP at 25 hundred RPM. There is very little difference between the VA and this UAS, and many parts are interchangeable. This UAS proved to be the culmination of Lauson’s endeavors in building air cooled overhead valve engines; and the Lauson Manufacturing company did not choose to build other air cooled F-Head engines during the remainder of its existence. Lauson built the Model Type UAS from 1933 through around 1940. This engine is an enhanced Model Type VA in almost every way; many internal parts are shared between the VA and UAS. Even externally, this engine has many castings that carry a VA casting designation. Unlike the VA, the UAS comes equipped with a rocker arm cover. Like the VA, air circulates down past the cylinder head, down past the cylinder cooling fins (enclosed by the sheet metal cylinder wrapper), through the duct work on the side of the engine, and out through the vanes of the flywheel; thus cooling air circulates in exactly the opposite direction that it does on most “modern” air cooled small engines. When visually comparing the UAS with the VA, the immediate difference you see in these engines is the redesign of the magneto drive and governor. On the VA, these are two separate assemblies while on the UAS they have been combined into one unit. The engine has larger valves, and the opening in the intake and exhaust manifolds are larger that it's VA predecessor.

The engine pictured is from my personal collection. You may view other pictures of it by clicking Here

UW


This engine has an 1/8" larger cylinder bore than the VR and UAS engines. The UW is rated as 4 HP at 2000 rpm. The construction of this engine is similar to the UAS engine but it is a water cooled engine.

This engine was built from the mid 1930's through toward the end of the 1930's.

UWR


The UWR is the marine version of the UW.

ZW


The ZW is built much like the UW with a slightly larger cylinder bore. The ZW was rated as 4.75 HP at 1600 rpm to 5.5 HP at 2000 rpm. It was built to be an inboard boat engine and was available with a reversing gear, a clutch, and a bronze water pump.

This engine was built from the mid 1930's through into the early 1940's.

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