Mercury Capri is smoking

Answer 1

A common enough problem with this engine.

They tend to wear out the ring groves in the pistons, just replacing the rings won't do much, as the new ones will still flop about allowing blow by.

A new set of pistons and rings will usually do it, unless the cylinder walls are worn.

So if you buy a set of standard size pistons, make sure you can swap them for oversized, if once you get the head off it needs a rebore, be sure to keep the box pristine

Its a one day job if you are comfortable working on an engine and can easily be done in the car. If it needs a rebore its engine out time. Be sure to run a degazing hone down the bores first, so the rings will seat properly