Is it valves or rings ? Options

[jsteele22]

My '76 2.0L is putting out a little smoke on hard acceleration. Is there a way to tell if the oil is leaking past valves vs. piston rings ? The old trick I always heard was to test compression, put a little oil in the spark plug hole, and retest. But that won't work on a horizontal cylinder.

My hunch is that it's the valves, but only because its easier for someone (PO, not me !!!) to screw them up by not doing regular valve adjustments. My records are a little patchy, but I think the engine was rebuilt less than 50k mi. ago. Any consensus on what tends to go sooner ?

Thx

[Brett W]

Bad valve guides will show up on start up. If you see a cloud of smoke when the engine starts up it is usually attributed to sloppy guides or in real engines, bad valve stem seals.

If the engine is tired usually you will get blow by at higher rpms and you will see it in the rear view mirror. A compression check won't necessarily show bad rings unless there is a mjor problem. Leak down is a much better indicator of engine health. But you can look at plugs and exhaust pipes as well to see signs of sealing issues.