What should the compression be on a Briggs & Stratton 17.5 HP engine OHV. Mine is 50psi. I trying to determine why my engine smokes under a load.

What happens when you do the compression test again with a bit of oil in the spark plug hole? C increases usually rings, doesn't change then usually valves. Smoke on start-up valve seals.

What color smoke?

Have you checked valve clearance?