Blows white smoke, but only when cornering

Blows white smoke, but only when cornering
I have a '78 280 CE, 6 cylinder, double overhead cam, with 190,000 miles. After driving for 30+ miles at 55-65 mph on a straightaway and then decelerating to make a 90 degree turn, an ENORMOUS cloud of white smoke blows out of the tailpipe which lasts for 8-10 seconds. After having embarrassed me totally, it's fine until the next 30+ mile trip with a turn. I can drive in town at 35-45 mph for hundreds of miles with no problem, but as soon as I drive for 30+ miles at 55-65 mph on a straightaway and then decelerate to turn, the smokescreen reappears. Any suggestions on what to tell my mechanic to check out?

with this type of engine and that many miles, I suspect that you are drowning your exhaust valve stems in oil while braking for a corner, if you are driving quite aggressively, and the valve stem seals are no longer up to the task. Have you ever seen an old V12 Ferrari blow smoke after every corner? (I used to see it a lot at Brainerd International 30 years ago when I was a corner worker and lived in Royalton) The design of that motor put the exhaust valve stems under oil anytime the car wasn't accelerating and they sucked it in like crazy under engine braking.

Basically, the question comes down to this: are you losing anti-freeze? If not it's probably oil going past the valve stems.