A little bit of white smoke in exhaust

I just bought a 79 320i and the past owner put an earlier model intake manifold with a twin barrel Webber on it. Now the valve cover breather tube was connected to the bottom of the air cleaner and there is no pcv valve in line. When I pulled off the cleaner there was a build up of oil on the bottom plate. It seems that as the vacume pressure builds the valve cover spits a little bit of oil up the tube and the carb sucks it up the rest of the way.

It seems to smoke a little only during start up so does this seem like a logical explanation