Though the major cab and fender sheet metal change began in mid 1947 (Advance Design), both the Chevrolet and GMC trucks kept their same proven six cylinder engines as used in prior years.
The base engine in GMC light trucks was the 228 cubic inch inline six cylinder introduced in 1939. This overhead valve unit had a full pressure oil system with its rod and main bearings lubricated from drilled lines within the crankshaft. Their high oil pressure is reflected on the dash gauge reading 0-50 pounds.
This family of engines during the Advance Design years also produced the 248 and 270 cubic inch units. The cylinder diameter in their main difference. They all share the same overhaul gaskets, water pumps, oil pans, distributors and side plates. On GMC, not Chevrolet, the cubic inch is the first three digits of the stamped serial number on the flat surface behind the distributor.
Chevrolet’s six cylinder used during most of the Advance Design years was very different from the GMC. Its standard 216 cubic inch engine was a result of continual improvements since the first Chevrolet six cylinder began in 1929. The 1940’s 216 truck engines were almost identical to that in the Chevrolet car. Therefore, millions of 216’s were on the road by the beginning of 1947. Their basic design and easy maintenance made them one of the greats in lower priced vehicles. When used on the roads of that era, they provided dependable service both on the farm and in the city.
The 216 engine was the standard power plant in the 3000 and 4000 series trucks. Its big brother, the 235 was optional on the 4000 series and standard on the 5000 and 6000 series. It is almost identical to the 216 but the increased displacement gave the needed extra power to work trucks. The 235 truck engine was not used in pickups, however, was matched to the Powerglide transmission cars with some modifications between 1950-53.
These 216 and early 235 are designed to operate without oil lines drilled in the crankshaft to lubricate their bearings.
The early 235 should not be confused with the more famous later 235 full pressure engine first introduced in Powerglide Chevrolet cars and the Corvette in 1953. During this transition year trucks continued to have the lower pressure design. By 1954 the full oil pressure 235 became the standard of the Chevrolet fleet. It was modified for trucks by using solid valve lifters in place of the hydraulics in cars. The camshaft gear was changed from fiber to aluminum.