I took out my 1973 today and had an eventful ride. This is the one I got off of eBay in March that was delivered with 7 quarts of oil in the sump. I drove it for a couple hundred miles and dried out the exhaust system.

It has two 40 Webers and was running fairly well today for an hour.

As I was about to park for a break in the ride, huge amounts of white smoke poured out of the exhaust. I tested the exhaust to see if there was oil that would condense on my fingers, but the smoke was dry.

I smoked my way over to the interstate to get to my mechanic. You all know what happened... The exhaust was now spotless. We couldn't to get it to smoke at all.

So off down the road, and 20 or so miles away, it happened again. Back to the shop... Spotless exhaust again.

My mechanic's theory is some old oil settled into the system some where and when it gets hot enough, it burns off.

Thoughts?

White smoke is usually too much fuel. Blue-ish smoke is oil.

I had a smoke screen of white smoke once. Turned out to be a stuck injector.

Hmmmm, maybe why my gas mileage is not too good. I'll check it.

Just a thought, but might check the top of your heat exchangers for burnt oil, right under the valve covers. If you were getting on the throttle and it started smoking, that could have been it...