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MG MGB Technical - emissions controls

Hello fellows, Over the last 3 months I sold my precious 52TD, money reasons. That being said there was some money left over and a need for a project, so I picked up a 1980 B found under cover for the last 8 years. fuel pump, water pump, all filters, all fluids, top, and new interior. Paint was new and buffed out beautifully along with new chrome spokes, it simply looks great. Now the problem, emissions pump was removed by PO and having many B's, midgets, healy's and of course T's all with SU carbs this has a zenith-stromberg water activated choke and won't start without a shot of starting fluid, cold that is. Once running and warm all is fine. What I would like to do is remove aqua choke and all related hoses, canisters, and EGR valve. In other words all the hub-bub that came with the car in 80 and simplify as well as keeping the Z-S carb. Can anyone help me with this project? Haynes manual already on the bench but no help in this way.
Thanks, Gary L. Emes
gary emes

You would be better off installing a single 1 3/4"SU in place of the stromberg.

Rich McKIe

Rich, I've heard good things about webers as well but if at all possible the fix would be making the zenith work or is it hopeless. Since it is already paid for maybe a tweek and a manual choke, sound possible?
gary emes

I have a '79 that has been desmogged and still running the ZS with a manual choke conversion. You will also need to disconnect the TCSA switch and run the vacuum line directly to the intake manifold. John Twist at University Motors has how to info at his web site that you can get by searching through the technical questions. I have some info that I could email you. Contact me if you wish.
Larry Youngblood

Hi Gary.

Having a UK car, I don't have the auto choke, but they usually work by a bimetal coil winding around as the water warms up, then pushing a peg to turn the shaft. It should be possible to cobble up some way of pulling the choke on and off with a cable if you examine the mechanism.

There is some adjustment if you have a manual, but check that a line on the choke body lines up with a line on the bit you can rotate if you undo the 3 screws, if that makes sense!

Is there a trick to setting the auto choke like pushing the pedal all the way to the floor once before you try starting the car that you neeed to do?
I remember having to do that with some old Fords.
Martin Layton

Gary; It it runs OK after you get it started you may want to attempt a repair iof the choke. These articles explain how.

Clifton Gordon

Gary. There are parts of the emissions control system which are both useful and cause no drain on the engine's power. The charcoal cannister(s) and the lines to the carb fuel bowl vent, the gas tank and the rocker arm cover are all very useful and do not rob the engine of any power.

As to the Z-S carb, I ran one for 5 1/2 years on my original MGB, a 79 purchased new. It ran fairly well, but, in those days, it was still possible to have it professionally maintained. Today, I see very few people still running the Z-S and most of them have converted over to the manual choke. The SU HIF-6 carb is, in my opinion, a better carb than the Z-S, but, it is expensive. The Weber DGV conversion, which also requires a new exhaust manifold or header, is not a bad system. The best system is to convert to twin SU carbs and this conversion is often discussed here.

Also discussed is the use of socket headed set screws to plug the holes for the air rails. Any holes in the existing manifold, where emissions lines are connected, will have to be plugged in some manner. Methods range from using a short length of hose, plugged at one end, and two hose clamps, to drilling and tapping the manifold for a plumbing plug. The latter makes a more competent looking job, but requires the removal of the carb and the combined intake/exhaust manifold from the car to prevent swarf (bits of metal) from being drawn into the engine.

Given a choice, which I do not currently have due to being required to meet emissions testing standards (both tailpipe emissions and "equipment inspection"), I would run the stock carbs and exhaust system from the chrome bumper MGs of about the 1962-1968 era. If you have such a luxury, that is a good place to start your efforts.

Les Bengtson

Don't throw the emissions gear away. I have been getting my car inspected since 1998 without the smog pump. It still has the charcoal cannister system. Four days ago I took it in for inspection and it failed because it didn't have the smog pump. No emissions test here but they do a visual. I had to bolt on the pump and gulp valve to get a new inspection sticker. After it's 35 years it doesn't have to have an inspection.

Clifton Gordon

Thankyou for the comebacks, they have given me a direction. Some more homework and tinkering will get this done. Emissions and inspection sticker are not an issue just cleaning it up and an easy start. It's refreshing to see enthusiastic participation as was the norm in the "T" thread. Any other comments on this carb and all of its peripheral clutter are welcome. Thanks again. Gary L. Emes -1980 "B"- Which goes like hell compared to the "TD".
gary emes

This thread was discussed between 04/11/2006 and 05/11/2006

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