strange smoking problem

[rix116]

1974 450 SEL, 256,000 miles. Down on power, uses a little oil
(but not excessive). Recently a strange problem has developed.
When I start the car cold, everything is normal. No visible smoke.
Then I'll drive about a mile or two. First couple of times, I'd drive to a store, shut it off, come out, start it and there would be an
excessive cloud of blue smoke. Then as I drove on there would be no smoke. Last couple of times, it would start (no smoke), then after 1 or 2 miles at most, if I stopped at a light and then accelerated there would be the excessive amount of blue smoke. Drive on and no visible smoke. When I say excessive, I mean a big cloud, so much that if there were a cop behind me he would probably stop me. But at cold initial startup and when the car is warm there is no visible smoke.
At first I thought there might be a stuck ring. But because there is a regularity to the problem (only does it 1 or 2 miles after startup) I don't think that's it. Also, wouldn't seem to be valve guide seals, because wouldn't that smoke right at startup?
Might there be some emissions related thing that is sucking oil
somehow, or a leaky power brake booster or something?

I'm stymied. Any ideas?

[Rockman59]

Sounds like a classic case of valve guides/seals being worn out. My car would emit a little smoke at startup but it really put out a cloud after idling for a few minutes at a traffic light. Oil consumption was light. Car ran great. But the smoke finally make me do the repairs.

[Paulwho]

rix166,
Another possibility is when a cam oiler tube pops off, the valve cover slowly floods with oil and then the intake guide suck the oil into the combustion chamber. This would take the 1 to 2 mile drive for this to occur. The oil fills the rear of the cover and overloads the intake seals. Oil would be noticed on the rear spark plugs of the affected bank. Additionally this car did not smoke at cold startup.

[pmckechnie]

I had this exact problem on my 84 500 SEL.
Turned out to be the modulator valve in the transmission.
The valve is located on the left side close to the shifter linkage. It has a vacumn line hooked to it.