whats the hose thats is comes off the passenger side of the engine that connects to the intake manifold on my a12, it also passes through the standard air cleaner bracket and appears to have a valve in it, no real reason in asking just wondering, i couldnt find it in book (probably not looking hard enough) but anyway.

Just a breather, I think that there is a strainer assembly attached in 1973+ models.

It burns off the oily fumes that come out of the rocker cover. Better to burn them, than to let them off into the atmosphere.

From your descriptoin it sounds like the hose that passes crankcase fumes from the rear of the block up to the PCV valve [positive crankcase ventilation]

This valve should be clearly described in your owners manual & workshop manual.

There is also a line running to the booster, but I am pretty sure it mounts to the firewall. The PCV is mounted directly under the carby.

That'll be your vacuum hose.......supplies the pressure differential to allow your brake booster to work.

Lots of Hoses

But to be more helpful.

Here's a pic from the Nissan South Africa Site:
PCV hoses picture

It seems the question was wrong, and both Dodgeman and I were correct

thanks, i had a look in my workshop manual and it was stearing me right in the face.