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

[billd]

The usual way do diagnose a compression problem is to do a leak-down test. Put the compression fixture on your air compressor. Insert the other end in your spark plug hole. Rotate the engine to TDC of the compression stroke for that cylinder and turn on the air. The differential compression reading indicates how much you're leaking. You can then listen to hear where the air is coming out. If its coming out the crancase breather its rings. If its coming out the intake or exhaust manifold its valves (or guides).