Hey Folks,

I installed an A/F ratio gauge and O2 sensor in my '68 Dart about a month ago in preparation for EFI installation.

I'm currently running a mostly stock (internal, MP 244 cam) motor with a Holley 500 carb, recruved dist, and Dutra Duals into 2.25" with a Y into a single 2.5" out the back.

I spent some time rejetting the carb for best power and mileage using the gauge, and I gained 1-2 mpg in mileage and a couple of tenths on the 1/8th mile dragstrip. It was too rich. I'm now getting 23 mpg on the hwy and 15 or better in the city. Granted I had not optimized that carb for this engine buildup, but it was very easy to do using the gauge rather than a lot of "ear" tuning.

I drove it (or my buddy Nathan did) to the Wilkesboro Slant race. That tank of gas was 340 miles and it ran 9 passes with some idling, and used 16.0 gals of gas...

It's a Sunpro gauge ($30 from Advance store) and a Bosch 1-wire O2 sensor ($30, ask for an early 80s Celebrity/Cavalier). Got a weld bung ($1) and drilled a hole in my headpipe about 14" from the front Dutra manifold exit and welded it in. It warms up the sensor in about 1-2 min.

Lou

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Home of Slant6-powered fun machines since 1988

Wait till you go wideband, thats where the fun really begins

Wide band???
Tell me more

A standard O2 sensor is optimized for a 14.7:1 air-fuel ratio, the best for emissions. It can tell you if you're too high, too low, or about right, but it isn't very useful if you get far away from there. Wideband O2 sensors can read across a much wider range, from around 10:1 or so to somewhere out past 16:1 (I'm not sure exactly where it loses its usefulness, but you'd never set a car to run that lean). They make it much easier to tune for maximum power.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

The only problem with many 'good' wideband O2 sensors is they cost some bucks, but they have a better range to work from and I think most are the 'pre heat' type. I notice most EFI 'kits' from the big companies (DFI, Holley, etc...) have one included in their kit (probably why the kits cost $$$).


-D.Idiot

There are expensive ones but there are cheap ones too. I believe the one Ultramegasquirt uses is less then $50.

So what is your cruise A/F? How do your plugs look?

Mitch

Can anyone suggest a parts store application for a modestly priced wide band O2 sensor. (Like the $50 item ultramegasquirt uses) I can't get anything but dirty looks from the parts stores without a year and model.

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1980 Aspen 225 super six

Exactly. I have this same problem when trying to order odd parts that I'm
using was from in different vehicles.

This is why more information is needed when using different parts successfully. Good example vapor separator unit. Anybody know where it's still available and what used in?

Cheers,

Wizard

Check http://www.megasquirt.info/UMS.htm

Wideband sensors aren't as easy to use as narrow bands, you need a seperate controller. You can't just plug it in your exhaust pipe and hook up a gauge.