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MG MGB Technical - I need help with hose routing.

Hi,

I just finished rebuilding an engine in a 1975 MGB for a friend.

The air pump and associated polution control equipement had been removed some 10 years ago.

The breather pipe from the front tapped cover was opened to atmosphere.

I do not know where this breater pipe should be routed to.

The Haynes manual doesn't show a clear picture of the "emission control" hose routing, nor does the Moss website.

Could someone help me!

Layne Wilson

Layne Wilson

Layne,

if there are HS/HIF 4 carbs installed, the pipe goes to the carbs just downstream the butterfly. A Y connetor splits the pipes for both carbs and is positioned ahead of the front carb.

If a CD Stromberg is fitted, it might be the easiest way to route the pite to the air cleaner housing and try it this way or change to a (even better) single HIF 6 that will acept the hose as the HS/HIF 4 do.

Ralph
Ralph

Hi Ralph,

The carburetor is a Zenith/Stromberg.

There is an intake manifold port just to the left of the EGR valve, towards the front of the engine, which has been blocked off with a 3 inch piece of hose with a bolt in it.

There is another blocked off port into the base of the right side of the carburetor towards the firewall on the intake manifold side of the throttle plate. This port is approximately 10mm (3/8) or a bit larger.

I know that what I need to do is to create a functioning Positive Crankcase Ventilation system, but how to accomplish this I am not sure about.

I cannot simply dump the flow from the breather pipe straight into the intake manifold or at the base of the carburator without some kind of control valve.

Based on older American vehicles it seems that this breather pipe should take air from the atmospheric side of the air filter, circulate it through the engine, and then back into the base of the carburetor, by way of a PCV control valve.

There is still a hose from the back of the tappet cover over to the cannister located at the back right corner of the engine compartment.

Is there any place I can go to get emission control schematics on various MGB's? It appears that an emission control system was added to this car so it could meet 1975 Canadian polution requirements.

Any help in sorting this out is appreciated.

Thanks---Layne Wilson
Layne Wilson

This thread was discussed between 20/09/2006 and 21/09/2006

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