[Mgs] MGB valve cover/crankcase venting

[Paul Hunt]

Which carbs?  From October 68 the original SUs had breather ports coming off 
the top of the throats, connected to a Y-piece, and then piped to the front 
tappet chest cover.  The rocker cover should have a vented oil filler cap 
fitted and any port on the back sealed off.  Alternatively you can keep the 
sealed filler cap and put a small filter on the vent at the back.  The 
former is neater and what was done to non-emissions cars, but the latter 
makes it more obvious what has been done.  In the former case if the filler 
cap happened to be replaced with a non-breathing type there would no longer 
be any crankcase ventilation, just vacuum, which could increase oil burning 
and result in internal condensation and corrosion.

Between Feb64 and Oct 68 a PCV valve was mounted on the inlet manifold to 
give the suction, and piped to the front cover or tappet chest cover.  The 
rocker cover arrangements would be the same as above.  But the PCV valve is 
troublesome, if you have the carbs with the breather ports that is a much 
better arrangement.  But if you have carbs other than the SUs, like Webers, 
you will need a PCV valve anyway for proper ventilation.

PaulH.

----- Original Message ----- 
> Can anyone tell me the proper way to pipe up the valve cover vent and the
> crankcase vent on an MGB with no emissions parts?