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MG MGB Technical - SU conversion

My '79 ex USA (CA spec) B. normally would have a Zenith carb but instead there is what seems to be one "large" SU of which I do not know the type. It's running so I don't have an immediate problem but I am worried about what settings to taken when servicing the car. Does anyone know how to identify the SU and what reason the previous owner might have had to replace the zenith by ONE SU (I could understand two) aside maybe from the manual choke?
Another thing is a cylinder under the dash. It says Inertia switch. What is it for because I can not find anything about it's function.
Carl

Does it have an external or integral float/fuel bowl? If it's external, it's probably an HS6. If it's integral, it's probably an HIF6 or HIF44 (later replacement). The inertia switch is intended to shut off the fuel pump in the event of a roll-over (if it's the one I'm thinking of). If it's not adversely effecting your operation, then I'd just leave it.
Barry Kindig


Carl,
Just an FYI.
Another roll-over device (mechanical) is located under the bonnet (hood) on the tray next to the brake/clutch pedalbox. Fuel line enters and exits it and it is designed to stop fuel flow in event of a roll-over. Consider bypassing this one as it is prone to leaking, if it hasn't been bypassed already.

Mike
'79B
Mike Janacek

Carl,
Look closely at the intake/exhaust manifold. If it appears to be one piece, but still utilizes the traditional MGB twin downpipes, then chances are you have a setup taken from the Austin/Morris Marina of the early 70's It is a much better single carb set-up than the Zenith single carb, particularly in the area of exhaust manifold design. IMHO...enjoy the absence of the Zenith.
Cheers,
Pete C
Pete c

The Zenith can be replaced by the single SU HiF-6 as fitted to the Austin Marina. This is a worthwhile conversion because the SU is a functionally superior product and low emission conditions can be easily accomplished with it. I have encountered Zenith carburentors on many cars including Mercedes products, but I have never met anyone who was truly happy with them.
Charles Edwards

This thread was discussed between 27/05/2002 and 28/05/2002

MG MGB Technical index

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