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MG MGA - O2 sensor

A local engine builder suggested installing an O2 sensor in the exhaust pipe, as the best way to tune the mixture. Has anyone done this on an MGA? And how would you actually read the sensor?
Art Pearse

You either need to use a electronic reading tool built for the purpose or an addaptor that will let your laptop computer read it. Moss and several others sell exhaust gas analyzers that are in fact an ox sensor and the electronics package. You just stick the sensor in your tail pipe.
J Heisenfeldt

Yes, with excellent results. Unlike the "probe up the tail pipe" units, an on board rich / lean indicator gives real time readings on the road. I ended up changing from MB needles to #6's. I'm running an 1800 in MGA regalia.
D Sjostrom

DS, can you share the sensor model and readout apparatus with us?
Art Pearse

Any type of probe will read both carbs as a unit ??
I haven't been able to completly isolate one carb to read them individually. Is there a method ? thanks Sean
S Sherry

You would need at least two O2 sensors. One in front branch of exhaust manifold would give you results of the front carb (mostly). One in rear branch of exhaust manifold would give you results of the rear carb (mostly). One in center branch of exhaust manifold would give you results of both carbs together as the center branch exhaust from #2 & #3 cylinders.

Also #1 and #2 cylinders may not get exactly the same mixture because the siamese intake port and valve overlap will treat the two cylinders slightly differently on intake. Ditto for #3 & #4.
Barney Gaylord

I was thinking of locating it on the pipe, near the manifold. Obviously it only gets an average, but plug colours could tell the balance.
Art Pearse

Here are photos of my installation. Barney is correct. You'll still need to set up the carbs properly, check the balance of the dashpots, set the idle and check the spark plug colors.


D Sjostrom

Here's the other photo.


D Sjostrom

I know, I know, each to his own and all that...but the box with all the LEDs on it just looks so wrong on an MGA dash to me. Sorry! (ducking and running)
Andy Bounsall

Andy,
It's Magnetic! I hide it behind the dash when not in use.
D Sjostrom

Ah, OK. Now I'll be able to sleep tonight. :)
Andy Bounsall

Is this thread about an MGA or a moon rocket !!
All these probes and readouts sound a little inconsistent with a 4 cylinder Morris Minor engine fitted with twin carbs!!!
Neil
n ferguson

All, read the article by Robert Goldman on page 3 of the Spring 2009 British Motoring. I think its available on the Moss website if you don't get the mailer.
George

G Goeppner

We use these in the race cars as an aid to setting mix. In that case we still use leaded gas so you just put them in while tuning.

We also usually install them downsteam of the pipe join, although Barney's method does give more accuracy especially in situations where oddball head design tends to give unequal cylinder distribution.
Bill Spohn

I forgot to add that I remove the sensor after tuning so as to eliminate the restriction caused by the sensor.
The only issue I have with a dual sensor setup is the area taken up by each sensor is a significant part of the port area which could introduce an increase in back pressure. This might affect the mixtures once the sensors are removed.
D Sjostrom

This thread was discussed between 17/04/2009 and 23/04/2009

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