1988 Honda Civic Smoke

I recently replaced a cracked valve, the distributor housing, spark plugs, distributor cap, rotor and spark plug wires. The car runs perfect, if not better than before, but it now spits white smoke and smells like the engine is burning oil. Sometimes, when driving on the freeway for about 30 minutes, the check engine light comes on and the smoke stops.

Do you have any ideas on what the problem is with my car and how I should go forward to fix this?

Thanks!