[Mgs] MGB valve cover/crankcase venting

[Rick Lindsay]

Paul, as usual, you knowledge astounds!

Here's some information that might help with your
recommendation for MY car, not Danny's.  Your previous
note addresses that.

My car is a '70 US-spec Tourer but under the bonnet,
it is a bit of a Frankenstein's creature.  The engine,
I believe, is a '65 18GB.  Here's the evidence for
that call, but please share your opinion:  

+ The carbs are AUD135F.  Granted, the carbs could be
anything but original.  

+ The head casting - which also may not match the
block - is casting #565394 which may have been used
across the entire range of the species, so probably no
help there.

+ The engine is set up for a generator, but now has an
alternator installed.  The car is (now) negative
earth.

+ The starter is the Lucas M418G inertia engaged type.
 A starter solenoid has been added to the wheel-well.

   And here's the kicker that confines my prediction. 


+ The valve cover has the riveted-on "MG" and "patent"
plates.

   That's it Paul, the only evidence I have (from
external observation) of the age of the engine.  And
of course, the engine number plate is missing.

Now, to the crankcase ventilation;

  My earlier note contained errors (as may be usual). 
What I called a "gulp valve" is really the "crankcase
emission valve".  The bottom of the valve is plumbed
to the inlet manifold.  The side port of the valve
connects to the hose from the forward lifter gallery
cover.

   Paul, my worry is that the crankcase emission valve
may not function as designed, allowing a vacuum leak
to the crankcase, thereby leaning out the mixture. 
Yes, I have carefully rebuilt the valve and it looks
good but 'looking good' and 'working correctly' are
not the same thing.  

   So the question becomes, if I effective plug the
line from the cover to the valve, will the crankcase
'breathe' adequately at the stock filler cap?

Best regards,

Rick

--- Paul Hunt <paul.hunt1 at blueyonder.co.uk> wrote:

> The gulp valve is used with the air pump to reduce
> back-firing on the 
> overrun.  No air pump - no gulp valve.  Other than
> that the ventilation 
> arrangements should be the same as before, unless
> you have removed the 
> canister and other plumbing as well, in which case
> the suction side stays as 
> before (PCV valve up to Oct 68, carb suction
> thereafter) and the inlet side 
> uses either a vented oil filler cap and a sealed
> rocker cover vent, or the 
> original oil filler cap and a filtered rocker cover
> vent.  having open pipes 
> dangling down beside the engine goes back to the
> non-positive ventilation 
> used before Feb64, which can result in dust and
> moisture being sucked into 
> the crankcase, and condensation and corrosion.  If
> the engine and breather 
> system are working properly there won't be any oily
> crap going into the 
> engine.
> 
> PaulH.
> 
> ----- Original Message ----- 
> > I am presently doing a valve job on my '70 B (with
> the
> > '65 engine) and as I reassemble the car I think I
> will
> > reinstall the gulp valve ...