Stick with a stock oil pump
I’m restoring a 1979 Firebird and am in the process of rebuilding a Pontiac 400 cid engine. Should I install a highvolume oil pump or a high-pressure oil pump? Or should I install a high-volume and high-pressure oil pump? The engine is bored .030-inches over and the crankshaft is .10-inches undersized. The car will be used mostly on the street.
You should install a stock specification oil pump. You will derive no benefit from a high-pressure pump or a high-volume pump or a high-pressure and high-volume pump, but you may do some harm.
It usually makes people feel better when they see the oil pressure gauge pegged but in reality a healthy engine (even a healthy high-performance engine) does not need a lot of oil pressure to stay healthy.
High-pressure pumps can in some instances damage components, including the distributor gear and camshaft. Similarly, a high-volume pump can actually damage components and lead to engine failure in some situations.
For example, a high-volume pump may pump oil out of the pan and into the engine faster than it drains back into the pan, leading to oil starvation. If your engine is rebuilt properly using quality components, a stock pump will supply more than enough pressure and volume.