Alfa Romeo Repair: white smoke, valve stem seals, power bleeder

Question
Thanks Stephen, I found the problem, it's was a leaking break master cylinder leaking back through the vacuum assist, check value and vacuum hose creating a huge cloud of white smoke intermittently. That brings me back to my next question, with the new master cylinder the pedal seem softer and I'm sure we got the all the air out and no leaks at the wheels. Should I order another master or is there something else to look for?-------------------------------------------
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-----Question-----
This is a new one on me. A friends Alfa spider, a 1977 I think, it will intermittently blow out heavy white smoke and then nothing again, Every thing seems to run great, even when smoking. It lasts for only a few moments, he already got a ticket for gross polluter. Bad valve seal, oil separator, O2 sensor?? help?
-----Answer-----
Valve stem seals have gone bad. Have an experienced mechanic change them without removing the head.

Answer
I should have picked up on the intermittent part.

I am sure you did not get all the air out. Use a power bleeder and bleed the right rear first, then left rear, then right front and then left front. And if you have 2 bleed screws in the front you bleed the one farthest from the pipe first.