Engines of Yore: Part 5.
Buick 8-80 and 8-90. created 06 January 1993
by Dave Williams [email protected]
Flipping through my 1943 Edition of Dykes' Automotive Encyclopedia,
we find a set of photos and some text on the Buick 8-80 and 8-90 of
late 1930s design. This is an overhead valve straight-eight engine
of moderate displacement. The block and crankcase are cast in one
piece of iron, and the cylinder head is another piece of iron. This
was by no means a given in the 1930s, where some engines used multiple
cylinder heads or barrels.
Buick used a crankshaft of 8 throws spaced 90 degrees apart, rather than the 45 degrees you might expect. Five very wide main bearings support the shaft, which has a front bearing, cylinders 1 and 2, another bearing, cylinders 3 and 4, etc. Thrust appears to be on the center bearing. Several throws have bolt-on counterweights, another feature often seen on very old motors. This allowed simpler casting and machining and posed no particular durability problem given the low RPMs typically used. Of particular interest is the harmonic balancer, an unusual piece for the 1930s. It consists of a two piece cast iron ring bolted around the rear crank cheek of #1 throw, well inside the cylinder block. The origin of the flexible material is not given in my sources, but I expect either oilproof rubber or leather.
Oiling is full pressure, with a gear driven pump attached to the center main cap. An oil filter was used, but it was of the "bypass" type, treating only part of the oil. Interestingly, the filtered oil was fed to the rocker shaft. The main bearings oil through a tubing manifold which attaches to the bottom of the main caps. The connecting rods oil through drillings in the crankshaft, as per modern practice. The wristpins are oiled by crankcase oil mist, also as per modern practice. Each connecting rod also had a "squirt hole" to provide extra lubrication to the cylinder walls.
The oiling system also includes a "temperature regulator", which we would now call an oil cooler. The Buick's was very sophisticated - the first hot water available from the engine went to the oil heat exchanger to warm the engine oil. This brought the oil up to operating temperature rapidly in order to boil out fuel and water contamination. Old-timey oil wasn't real good stuff, and the Buick tried to take good care of it. When the oil got warm enough, the radiator water was used to cool the oil. The system Jaguar is so proud of on their V12 is a slightly less sophisticated arrangement. The coolant circulated continuously with no conventional thermostat. Temperature control was via thermostatically operated shutters on the radiator.
The camshaft is set low on the right side of the block and driven by helical gears from the crankshaft. Conventional cylindrical cam followers are used, with roller tips against the cam, something Detroit dropped and then picked back up on in the late '80s. An extra spring is incorporated within the follower body to function as a peculiar sort of rev kit; the spring keeps the valvetrain together if the engine is revved high enough for valve float. Pushrods are solid, with the rockers mounted on and oiled through a shaft. The valves used normal-looking split keepers and dual valve springs.
The water pump, generator, and distributor are gear-driven from the front of the engine. The fan belt turns only the fan. The flange between the water pump and generator contains an oil drilling to provide full pressure lubrication to the front generator bearing. This arrangement was undoubtedly more reliable than a forest of V-belts, particularly considering the state of the art for V-belts in the 1930s.
Connecting rods were very long, with conventional caps and through bolts. The piston pins were taper bored at the ends for lightness. The clutch used dual discs and a coil spring pressure plate. Carburetion was a two barrel updraft device, nowadays seen only on stationary or farm engines. Though thoroughly obsolete by modern standards, the updraft carburetor ensured only vaporized fuel entered the intake manifold; any cold droplets would fall back into the carb. Updraft carbs were particularly famed for smooth idling and low RPM operation.
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