'76 318 smoke...

One possibility you wont want to hear: You may have a microscopic crack in a cylinder or a head.
When the engine warms up the expansion of the metal may be enough to partially reseal itself. White smoke is coolant, nasty smell is coolant.
Next time the engine is cold remove the radiator cap and bring the engine up to normal operating temperature. Watch the coolant for a very fine bubble or foam.
Check each sparkplug for color variance. Clean/light tan shows optimum performance.
Hope this helps you solve your problem.