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MG MGB Technical - Air pump

I found some inputs in another thread, but still have some questions. I just bought a late 1980 MGB, imported from Japan into Dubai with already removed air pump, gulp valve etc... (all the other components are still attached). The engine runs well, but seems to get rather hot. Somehow i am not sure if the air pump system is required for proper running of the engine. If off the throttle, the engine tends not to slow down (why?), but has no back fire at all. I would like to remove the catalytic converter. Would it require new tuning of the engine?
Any inputs? Many thanks!
Reto, Dubai
Reto Schlumpf

Reto;

You should check the archives. Search for "emission removal" and you'll see a lot of stuff on removing the emission equipment. I realize that yours is already gone, but you might want to check that it was done properly.

I'm sure you will also find plenty there on removal of the catalytic converter.

Chet
Chet Harter

Hi Chet,
Thank you for your comment.
I am just confused, because for many years I was driving a pre-rubber-boat. But now I have the only MGB in Dubai... and I just did a conversion to crome.
Does anyone know why the car tends not to slow down when off the accelerator? Has it to do with the missing air pump?
Thanks
Reto Schlumpf

Reto. The air pump does not affect engine opearation, to any great extent, if it is installed correctly or removed correctly. The removal of the air pump, properly acomplished, leaves the right hand side of the engine bay much less cluttered and makes it easier to work on.

The holes going into the cylinder head, near the spark plugs, should be plugged with set screws, cleanest installation, or hex head machine screws. The hole size should be 7/16"-20 tpi.

As to the lack of engine braking, or compression braking--the ability of the engine to slow the car when the foot is released from the acellerator pedal, this is not affected by the air pump. It is affected by a slipping clutch, however.

Do you have an overdrive transmission? My 79 recently began to do the same thing, from time to time. No engine braking, but, when I accelerated, it was like the clutch had been re-engaged. This problem has been diagnosed as either the one way clutch or the sun gears in the overdrive unit, both of which require the engine and transmission to be removed from the car and the gearbox to be disassembled for repair/rebuild. Another learning experience about installing, "used, known good parts".

Les
Les Bengtson

or sticking linkage
J.T. Bamford

Les, could it not be the carburater itself because the overdrive shifts very smooth and the gearbox is in very good condition too. I think it is rather the engine which reduces its rev. very slowly, could it therefore be the water chock?

The right side is plugged with set screws.

I am not familiar with the Zenith carb. It looks just rather complicated with all the hoses and connections.
Would it be advisable to change the carb for a dual SU or a Weber?
Reto Schlumpf

This thread was discussed between 19/09/2006 and 20/09/2006

MG MGB Technical index

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