Is it feasible and worth it to put one on a slant to fine tune the carb, etc?

The new exhaust manifold I put on the '63 has the O2 hole with a plug in it so that part's easy.

Good idea? Bad idea? What O2 sensor would be best? Can someone school me on narrowband vs wideband and what would be better?

TIA!

(Not a racer, just a basically stock car.)

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If you are tuning a carb that has a fair amount of "tuneability" (or "futzwithits"), the O2 sensor can help dial the mix in sooner, especially if used along with a vacuum gauge.

If you are on the cheap a narrow band 1 wire O2 sensor for $40 at Autozone for a S-10 4.3L Blazer can work well up to a certain point (at least you will know if your mix is off one way or another but only within a small amount of adjustment)...if your carb is way out, it can help you get it "close", and you can dial it in more if good at tuning with the vac. gauge and reading plugs.

The wide band is more expensive, but will give you the whole yardstick to measure the ratio (the narrow band will "fall off" or get stuck on either end of the limited scale if out by 1 degree or so of stoich), it will be able to show you just how rich or lean it is.

Depending on where the bung was located can determine how the sensor reads (closer to the manifold outlet or in the exhaust manifold is the industry standard). If using a 1 wire sensor liek the narrow band above the readings won't be good until the engine is up to operating temp and the mix has leaned enough to heat up the sensor filament and burn off any soot left over from the choke close/rich mix engine warm up sequence.

At least if you go to EFI, you already have the sensor in place.

Some caution to think about:

You can't use leaded gas and certain octane additives with the sensors as it will contaminate the sensor lead and it will stop reading correctly (sometimes they look like they are registering, but they are just sending impulses).
Using a high oxygenate gas can also throw the reading if you are not ready for it (I doubt you are going to run 5 gallons of e85 added to your regular gas to "see what it might do").
If you run the engine too rich too long the soot will clog up the sensor and you will have to replace it.
Remember also that engines have a 'curve', so the engine should not be "even stoich" all the time...it should be rich at cold start until warmed up, you should be slightly rich on accelerating or passing ( or more rich if racing!). Idle can be close to stoich. some of this also depends on your engine build (a wet manifold hyperpak likes things a little more rich due to the manifold and the fuel riding the runners, short runner and stock manifolds not so much...).

Good Luck,

-D.Idiot

I've had a narrow-band sensor and gauge on my AMC for some years - it just to warn me when something goes wonky. I don't think I could use it for tuning.

A lot of good information there, DI, thank you!

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I read some warnings about the stock sensor location on the slant exhaust manifold being too hot for a wideband O2 sensor, so we planned to stick it there for tuning and then take it off. Then we forgot and ran a whole 14-hr road race with it on. It still seemed to be fine until we accidentally fried it a month and a half later when testing our badly-wired kill switch.

Keep in mind that your A/F ratio will be slightly different in neutral than it will be under load. You can get things pretty close in the driveway, but then you'll need to take it on the road and see how things change.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing

AEM wideband

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V8?? We don't need no stink'n V8!!

This is why i also suggest the vacc. gauge...it will allow you to see what your throttle plate position is relative to the speed and physical conditions.

On the road you are subjected to:

Vacuum Advance per the load on the car (hills, flats, downhill, down shifts)

Whether the carb is in the mains, transition circuit, power valve enrichment, secondaries kicking in...etc...(would be bad to tune things and find out the vacc reading was so low that you were dialing in the mix with the power valve open all the time...)





-D.Idiot

Even on a 1bbl rig, if you have the option of adding an A/F meter, wide or narrow, do it!

Add the manifold pressure gauge, and you have the world by the tail.

If you have a GOOD vacuum gauge, you can use it to verify your valve condition, lash, and timing.

An A/F gauge, even a low end one, will tell you quite a bit about how those circuits Professor DI mentioned above. It's a solid tool for getting you in the ball park. Getting further may require some more extreme measures, but is unlikely to deliver an ROI for a daily driver.

More information is good!

This from a control systems twidget... Yep, I'm biased to getting every bit of info I can!

CJ

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Part of Tyrde-Browne Racing

I know I am alittle late to the thread but I say install a wideband O2 it makes a huge diffrence just by having the info when tuning. I have installed a couple on mine and freinds cars all being AEM Yugo. You want the digital numbers right there in front of you. There is other systems out there that will data log and record your info but the get pricey. I talked with a shop in town that tunes lots of imports, old and new mainly 6 and 4cyl cars. The head tuner said you get the most accurate reading 12 to 14 inches after the point the runners connect to get a measurement of all cylenders. I asked why so many factory manifolds had the bungs cast right in place. He said they where just cutting cost with ok results. If I was using a stock manifold I would not use the stock location I would go about 6" from the stock manifold to the downpipe. On my dutra dual I will be a few inches back from my y-pipe but that will be a ways down about where the clutch linkage is.