I have been having issues tuning my carbs. I finally decided to by a wideband air fuel package. I have searched and found several responses. I just want to triple check before I weld the bung. Is the area that is circled a good place to put the bung. I plan on putting it on the front side so it will not be noticeable from the rear- I just didn't have a picture of that side.

Looks OK. You want it at the merge. The only problem, for best accuracy the sensor should be 12-18 inches from the head. This theory does not work for a 914. So your next best bet is to wrap the exhaust with thermal wrapping. This will keep the exhaust gases hotter, giving better scavenging. Problem; Wrapping the exhaust will anneal the steel and cause it to become brittle. They will self destruct in time like a grenade. Wrap also voids most header warranties.

So... I think the location is perfect. Just pay attention to where the wire is going. Keep it out of harms way.

go to innovate web site and read o2 sensor installation guide. do not mount below 9-o clock or 3-o clock. 12 o-clock is best

Also put the sensor on the top to keep moisture from affecting it.

Thanks for the great advice

The comment about on top is correct due to moisture build up. You could also weld a bung on each side just before the collector flange so each side could be read. I used Bosch 3 wire sensors and GM weather seal connectors so the sensor can be unplugged when needed and the 12 volts help the sender heat up very quickly.

I am in the middle of installing a WB myself. I'm using a Bursch and welded the bung in the 12 o'clock position at the collector. Hope to have it done tonight.

I am very interested in your collective experience as I see VERY unusual results from my WB O2 from Innovate;
In a 1.9l L-jet motor with about 8.6 to 1 CR I get the following results from the Innovate display;
Idle - 22
Mid range (mid throttle) - 14
Full throttle - 8

Now, the car runs very well, so these reading don't make any sense?

Any clue as to what I did wrong?

My O2 sensor is mounted at the 3o'clock position so it is not optimal, but not bad.

I thought I read somewhere that if the O2 sensor was not powered then it needed to be removed from the exhaust system. Otherwise it would likely be damaged.

GM uses 1 wire sensors everywhere. They are not removed unless defective. 1 wire sensore do not have a heating element like a 3 wire, 5 wire or 6 wire. The 1 wire takes a few minutes for the exhaust to warm it up before it works. I run dual 1 wire O2's. One to the ECU and one to the gauge.

I thought these things were used mainly with computer controlled fuel injection. Can they be of mucn help if you use carbs? Is it worth the expense?

Cheers, Elliot

They are used as feedback loops for FI. If you run carbs, they can help you identify transition problems, mixture issues, lean condition, etc.

I'll be wiring the one in the bus soon.

The question about needing one with carbs is a good one and most of the vintage racers I raced with over the years had one installed to keep an eye on mixtures when running on a track such as CA Speedway where you are at full throttle for 45 seconds AND going around some heavy duty banking. These two factors can cause an engine to go lean quickly and burn a valve or piston very quickly. For an aggressively driven street car or DE car they can help prevent the same thing as there are many roads with nice long curves.

We always used Bosch 3 wire sensors and the last one I bought at Pep Boys was $40 or so and the GM type 3 wire water proof plug allows you to unplug the wires so you do not have to disturb the sensor or allow swapping the meter to the other side.

I've read from a couple of sources that you DON'T want a wide band too close to the head. That was true with the original O2 sensors, but the wide bands will fail really early if too close. Here's one article below on bung installation, recommending 1 meter (40") from nearest exhaust valve. Click to view attachment Also, Here's where I put mine on my Bursch.
Click to view attachment

You are running rich. Think about how this works.
Decelerating you have just shut off the gas so of course it is lean, you are only sucking air. No load so this is normal.
22:1 at Idle is a bit lean but it has no load so it is most likely fine.

Mid throttle will fluctuate and 14:1 may be about right. Try it again going up a slight hill for a proper reading.

Full throttle or part throttle under load, now you have a load and the reading becomes very important on our aircooled engines I aim for 12.5-13:1 they like a little rich as it helps with cooling. WC engine can run leaner and I'd aim for stoich (stoichiometric )which is 14.7:1. I love our long gradual hills as they are perfect for taking readings through the RPM range under part load. In a perfect world you should be hitting 12.5-13.5 through all RPM's going up that slight hill and when you are accelerating.

3 wire lambdas defiantly must be powered or removed. One wires don't need to be powered, but most one wire are narrow band and only read about 14:1 to 15:1 or close to stoich. Also one wires depend on the exhaust heat to work, this take more than a couple of minutes and on a new engine break-in you could damage the engine before your meter even starts working.
Using a 3 wire it doesn't care how close you are to the heads, it's measuring oxygen. On a one wire you would want it close to the head as it doesn't even begin to work till it's about 600*F. 3 wire is better on our cars for sure.
You could mount you lambda up to 8-4 o'clock, basically you don't want it sitting in a pool of water after shutdown.



Do you like pulling your plugs using the old school method to see if you're running lean?
I don't buy jets (unless I need smaller, not often), I have my meter and a set of jet reamers. I can fine tune a set of carbs in one afternoon and be done with it.

Great info

If you can get the full throttle under load up to 11 or 12 at the hottest the motor will ever be, it will make quite a bit more power and still be rich enough to be safe

11 is too rich, best power and cooling on an aircooled is right at 12.5-13:1

I've done this on my SDS 1.8 and 2.0 914 engines and a 2.7 nickies carbed T4 engine, all with full gauges. Plus a few other stockish aircooleds, T1 and 4.
Over 13.5 head temps start to rise, under 12 the car sucks gas and gets a bit doggy.

the innovate is fast. It can sample each individual gas pulse. for a more readable result, go into the software and SLOW DOWN the sample rate. this will give you a smooth, less jumpy reading that makes sense.

3, 4, 5 wire sensor must be powered whenever the engine is running!!!

carb jets clog alot. a wide band will show you this before damaging the engine

wide band is unbeatable for carb tuning and proper jet selection

Looks like I'll be looking for one of these wideband thingies. So, I can get one of these at a local FLAPS? What do I ask for? 02 sensor? I also need to look up "stoichiometric", what ever the hell that is.

What kind of exhaust, and where is the sensor located? Specifically, is it too close to the tailpipe? If you read the article I posted earlier Click to view attachment, it says that too close to the tailpipe and you may read lean at idle due to air being sucked in between pulses when the pressure can actually drop below atomspheric. They recommend 20" as a starting point, otherwise ignor the idle readings.

14.7:1

http://en.wikipedia.org/wiki/Air-fuel_ratio