317 cubic inch
- Cast nodular iron crankshaft supported by five bearing journals at 2.62inch
- Rod journals measured 2.249 inches
- 8.0:1 compression ratio and 205hp at 4200 RPM
- An improved Holley carb, high lifter cam, dual diaphram distributor and freer flowing exhaust
341 cubic inch
- Last only for 1955
- Increased bore to 3.94 inches
- Compression ratio of 8.5:1 with 225hp at 4400RPM and 332ft.lb of torque
368 cubic inch
- Introduced in 1956
- Increased bore and stroke to 4.00X3.66
- 285hp @ 4600 RPM with 402ft.lb. of toque
- Compression ratio is 9.0:1
- Larger exhaust valves at 1.64 inches, bigger fuel pump and dual diaphram distributor
- Black painted valve covers and air cleaner
- Following production year had slightly revised enhancements including 10.1:1 compression, Carter four barrel carb and a spin on/off oil filter
