Camshafts for oversize engines
Choosing a cam for a bored and/or stroked engine requires a bit of “fudging”. The same cam should, in theory, work for an engine that is oversize. The problem occurs when you increase the displacement by 20-30%. The engine now demands a similar increase in air/fuel supply which will require larger components (valves, ports, exhaust system, etc.). These modifications usually don’t occur due to the vehicle owner’s budget or lack of space to fit larger valves, etc. While larger displacement will guarantee more part-throttle and low-mid RPM torque, it is the higher RPM torque and horsepower that may require assistance. If you are trying to produce more horsepower from your oversize engine package via replacing the camshaft (a compromise), you need to choose a camshaft that will increase port flow. This is going to be achieved by opening the valves as quickly and as high as possible. So you are looking for a camshaft that has more lift. Due to certain design constraints, you may need to accept a camshaft that also has more duration.