Crank Case smells

[Sam]

hi everyone, hope you can help me with my Alfetta sedan (1979)
I've been getting a smell comming into the car when I'm at idle or driving slowly, but when I'm on the Freeway driving at speed, it's not a problem. (I guess it's blowing away and not comming into the car).

I think it smells like crank case fumes, but I cant seem to find out where it coming from.

I noticed the rubber gasket between the Air filter cover and the botton aluminum peice that bolts to the carbs was old and maybe leaking? so I replaced it with a new strip of rubber but No Bloody Good.

I then stuck a new sheet of rubber under the Oil filler cap to make sure it's sealing properly , but still NGB.

The stink is horrible and almost makes me sick ....
I have to drive with the window down to help suck the smell out  - bloody cold !

Anyone got any clues ..??