Klaus,

My car came with the pcv system closed off, by a previous owner.

The solution I arrived at was flame trap to manifold, with pcv valve in the line, and the oil filler cap to air filter, where the oil filler cap sucks in air using the carb filter to clean the air. It seems to work. I also cleaned the oil filler cap and the flame trap guts, and pushed some bronze wool down inside the flame trap cause it was gone.

I am pretty new myself, and like you I spent some time on the web looking for how this pcv system was supposed to work on my car. I found the following urls to be helpful.

http://www.brickboard.com/RWD/index.htm?id=1026109&show_all=1

http://www.vicwhit.com/spitfire/spittech.html

http://65brick.blogspot.com/2008/06/pcv-valve.html

http://www.triumphspitfire.com/weber.html

http://www.sw-em.com/service%20notes.htm#Engine