Can I use engine parts from a Pontiac 400 C.I.D on a 403?
The 403 and the 400 are COMPLETELY different motors. The 403 is a small block built from 1977-79 based on the Oldsmobile 350 engine. The stock 403 Olds, or 6.6 Litre, is rated at 185 hp @ 3600 RPM, 320 ft/lbs torque @ 2200 RPM, 4.351 inch bore by 3.385 inch stroke, 8.0:1 compression ratio. The 400 is a Pontiac engine based on the 389/421 engine from the early ’60s. The T/A 6.6 Pontiac motor produced 220 hp @ 4000 rpm and 325 ft/lbs torque @ 2400 rpm, 4.12 inch bore by 3.75 inch stroke. Nothing is interchangeable. Starting at the top even the carburetors have different part numbers and base plates. At the bottom the motor mounts are the same and mount to the frame rail cross member in the same place, but the motor brackets are different. On the sides the exhaust manifolds are not interchangeable, even the lead pipes line up differently. At the front the radiators are the same, but the fan shroud and radiator hose are different. At the back of the motor the good news is that the bolt pat
