Power Plant

power_plantDespite the fact that by the time production was ordered, the US had become involved in the war work started to convert the initial experimental models into production models straight away. A massive engineering project was undertaken by Chevrolet and involved almost 1,000 principal machine tools, most of them designed specifically for the job in hand. Parts and sub assemblies to supply the final assembly line came from eight Chevrolet plants in three States. Five other factories outside the Chevrolet Division served as sub contractors as well.

At that time the largest engine produced by the Chevrolet group was the 235.5 CID truck engine which developed 83 bhp net at 3,100 prm. With two of these engines power production was still inadequate so Chevrolet used two GMC 270 CID truck engines which produced 97 bhp net and 104 bhp gross each. Once production was ordered however, GM Yellow Truck & Coach Division, makers of the engines, confirmed that they were unable to spare the engines required because they were needed for CCKW Series truck production. Chevrolet therefore produced what was in effect a new engine albeit very similar and sharing many parts.

These new engines were redesigned and put into production by the GMC Plant at Pontiac, Michigan with cylinder blocks coming from GM Central Gray Iron Foundry in Saginaw which were then shipped out to the various divisions installing them. The principal differences were a number of casting differences to the exterior of the block and double main bearings at either end of the crankshaft. As the design was refined throughout production, several other changes were incorporated including alterations to the valve timing, valves and ignition timing to facilitate the higher revs used by the automatic gearboxes.