| GMC straight-6 engine | |
|---|---|
| Overview | |
| Manufacturer | General Motors |
| Production | 1939–1962 |
| Layout | |
| Configuration | straight-6 |
| Displacement | 228–503 cu in (3.7–8.2 L) |
| Cylinder block material | cast iron |
| Cylinder head material | cast iron |
| Valvetrain | OHV, 2 valves per cylinder |
| Combustion | |
| Fuel system | Carburetor |
| Fuel type | Gasoline |
| Cooling system | Water-cooled |
| Chronology | |
| Predecessor | Buick Straight-6 engine 223 cu in Pontiac straight-6 230 cu in Oldsmobile straight-6 |
| Successor | 324 cu in Oldsmobile V8 GMC V6 engine Chevrolet Turbo-Thrift engine |
The GMC straight-6 engine was a series of gasoline-powered straight-six engines introduced in the 1939 model year by the GMC Trucks division of General Motors. Prior to the introduction of this new engine design GMC trucks had been powered by straight-six engines designed by the Buick, Pontiac and Oldsmobile divisions of GM.
The new engine family featured a valve-in-head design, pioneered by Buick and also used by the Chevrolet division's contemporary "Stovebolt Six" engine. Many displacements were produced using three block sizes: "Group 1" (small), "Group 2" (mid-size) and "Group 3" (large).[1]: 15
The straight-6 engine was replaced by the GMC V6 engine in 1960, remaining in use only in certain light-duty models of the P-series step van until 1962.[1]: 27–28