Bung location for wideband o2 gauge

[68charger440]

I have another thread going talking about a tailpipe sniffer type wideband o2 gauge to tune my carb, but I am thinking maybe I should just go ahead and put a bung on the exhaust just downstream of the header collector.  As for installation and location, here is a quote from one of the kits I saw.

"GUIDELINE FOR THE LOCATION OF THE OXYGEN SENSOR
Below is a preferred method although it depends on the application. Weld the bung at least 24" downstream of exhaust port outlet or 24" after the turbocharger. It should always be before the Catalytic Converter. Also it should be before the X or H pipe if there is. Bung should be welded on the upper section which is located between 9AM or 3AM clock positions. Please check your vehicle for exhaust leaks, camshaft overlap and open exhausts because those would cause false lean readings. Do not have oxygen sensor exposed to exhaust gas and do not Pre-warm it. Not following these directions may result in premature failure of the sensor."

My questions are...
1. Does it really need to be between 9:00 and 3:00 clock position, and why? 
2. Has anyone used one of those bungs that don't have to be welded, or are they junk? 
3. I was thinking of putting it about 3 or 4 inches downstream of where the collector bolts to the rest of the exhaust?
Any thoughts?

[Troy]

1. Water and protection
The 02 sensor is heated so when the car is running it's fine. However, water condenses in the pipe as it cools and will ruin the sensor. Protection against ripping it off on something you run over.

2. I haven't used the weldless bungs. I researched then for a while but now I have a welder so I bought the normal bungs for all my cars.

3. That location sounds fine to me - but I'm far from an expert!

Troy

[68charger440]

1. Water and protection
The 02 sensor is heated so when the car is running it's fine. However, water condenses in the pipe as it cools and will ruin the sensor. Protection against ripping it off on something you run over.

2. I haven't used the weldless bungs. I researched then for a while but now I have a welder so I bought the normal bungs for all my cars.

3. That location sounds fine to me - but I'm far from an expert!

Troy

So if I put it on the lower half but remove it and plug the bung after each use then I should be OK?  I'm just trying to avoid dropping the whole exhaust to put the bung at or above the mid piont.

[Troy]

I suppose if you install it and only test in your garage then remove it you shouldn't have an issue.

Troy

[68charger440]

Thanks... I'm not a serious racer, just once in a while for fun so once I get it dialed in I won't touch it unless something seems off. 

[flyinlow]

Mine is about 6 inches behind the left header flange in a 3 inch exhaust pipe. Before the X-pipe. About the 10 o'clock position so it drains. Welded bung.  Has worked well for thousands of miles. With a dual plane intake the drivers side bank has two cylinders fed by one side of the carb and two cylinders fed by the other side. If there was a vacuum leak on the right bank it would be hard to see with my set up. The A/F ratio gauge is not my primary tool to find vacuum leaks anyway. I have thought about putting a bung in the right side , but have not done it yet.

[XH29N0G]

I run at 90 degrees (flat), and it comes in from the side into the collector.  I had it welded in and I do not have difficulty accessing it, BUT I am running hooker competition headers on a 383 and they do not tuck up nice against the floor, so I suppose it could be an issue with a better fitting exhaust system.  The A/F cable tucks up nicely under the floor and in through the firewall, so that is not an issue.  It is also not difficult to remove or replace to check calibration (which I only did once because the manual said I should, but I saw no change in anything).  So if you decide to install it at a different angle for tests and then remove it when done, I do not think you will have any problems.

[68charger440]

Thanks guys...  I'll let you know where I end up putting it.  I need to get the car up in the air to see how much room I have.

[68charger440]

I don't really know what to look for on these wide band gauges. 
I found this on online...http://www.ebay.com/itm/400862052433?item=400862052433&viewitem=&vxp=mtr
is this what I'm after, or do you guys have other suggestions?

[cdr]

that will work great !!!!

[68charger440]

I have a place about 8" before the X pipe where I might be able to get it in at 90 degrees.  It shouldn't matter if I go that far back, should it?
How much does it

[68charger440]

My system crashed and somehow posted when I was writing that last post.  
So to finish, what does it roughly cost to have a muffler shop weld a bung for you.  My welding looks like a 5 year old on a good day, and all I have is a crappy little wire feed welder.  Has anyone ever used one of those cheap oxy acetylene rigs from Northern tool or harbor freight?

[cdr]

20 bucks would be fair. &  At 90deg what i do is, drill the hole to fit the o2 bung , then hit the pipe on top side of the hole to change the angle & then weld it in , that will make the bung sit a tilted angle & keep moisture out of the o2

[500Jon]

Mmmm, just fitted one in my freinds Dodge 440 car, we put it slightly downstream of the 2-1/2 X-pipe...
Was that a mistake???
5J

[68charger440]

If you have any exhaust leaks up stream you could get a false reading, but otherwise I think you should be ok.  They sell some that you can stuff up your tailpipe, and they seem to work fine.

[500Jon]

Are you absolutely 100% sure?

Only pulling your leg...
Its a new S/S system and fairly sound, I hope?
I'm sure on his instructions it didn't mention in front of X-pipes???

They are for sure, a clever bit of KIT!!!
Best $200 of anyones money.
Must have saved that in better gas-miles already lol.
12 mpg instead of 10 mpg's.

[68charger440]

...and I thought nobody read those signature lines. 
I agree on the gas mileage.  Mine was at 6 mpg and fouling plugs all of the time.  I haven't checked my mileage since I dialed it in, but I bet I doubled it, and I bet that A/F setup paid for itself in the first month, not to mention how much more power, better idle, not washing my cylinder walls with gas, or the money spent on new plugs, and time driving the car lost because it was running like crap.

[myk]

Trying to understand how this works.  Don't you need two sensors, one for each pipe? 

[68charger440]

Not unless you are having problems on one bank and not the other.  Then it might help point you in the right direction.  I.e. If one bank has perfect a/f reading and the other is rich, maybe you have a fouled plug on the rich side, and unburned fuel is passing through the exhaust.

[BSB67]

I.e. If one bank has perfect a/f reading and the other is rich, maybe you have a fouled plug on the rich side, and unburned fuel is passing through the exhaust.

So, what do you think your gauge will tell you in this situation?

[68charger440]

I.e. If one bank has perfect a/f reading and the other is rich, maybe you have a fouled plug on the rich side, and unburned fuel is passing through the exhaust.

So, what do you think your gauge will tell you in this situation?

I think it would tell you that the side with a fouled plug will have a richer A/F ratio telling you to look at that bank first.  Or in a different example if you have an intake leak on one side you might see the A/F readings on that side go lean.  When I bought the bung for mine it came in a pack with 5 bungs and two plugs for $15, so that extra bung cost you a couple of bucks for another bit of diagnostic information. When diagnosing a problem more information is usually a good thing.

[justcruisin]

Not unless you are having problems on one bank and not the other.  Then it might help point you in the right direction.  I.e. If one bank has perfect a/f reading and the other is rich, maybe you have a fouled plug on the rich side, and unburned fuel is passing through the exhaust.



That's not necessarily the case, if you have a plug misfire you can see a high O2 reading - the sensor as the name suggests is reading O2, if the plug fails to fire it will exit the unburnt charge out the exhaust, including the unburnt O2. The oxygen content is greater than the fuel content so the sensor will show an excess of oxygen - indicating on your gauge a high number.

Personally I see two O2 sensors on a carburetor engine as unnecessary.

[68charger440]

Not unless you are having problems on one bank and not the other.  Then it might help point you in the right direction.  I.e. If one bank has perfect a/f reading and the other is rich, maybe you have a fouled plug on the rich side, and unburned fuel is passing through the exhaust.



That's not necessarily the case, if you have a plug misfire you can see a high O2 reading - the sensor as the name suggests is reading O2, if the plug fails to fire it will exit the unburnt charge out the exhaust, including the unburnt O2. The oxygen content is greater than the fuel content so the sensor will show an excess of oxygen - indicating on your gauge a high number.

Personally I see two O2 sensors on a carburetor engine as unnecessary, unless you have a DP manifold that completely separates each side, most performance engines even with a DP manifold don't completely separate each side, either through design or a spacer.

I can see that logic, but either way the readings would change from one side to the other and that would help you find your problem.  I'm not saying I would go real far out of my way to have one on both sides, but for 2 or 3 bucks you can have a plugged bung on the other side and swap the sensor as needed.  Just one more goodie in your testing toolbox.

[XH29N0G]

When I bought the bung for mine it came in a pack with 5 bungs and two plugs for $15, so that extra bung cost you a couple of bucks for another bit of diagnostic information. When diagnosing a problem more information is usually a good thing.

So did you install all 5 bungs?  pics?

[BSB67]

I.e. If one bank has perfect a/f reading and the other is rich, maybe you have a fouled plug on the rich side, and unburned fuel is passing through the exhaust.

So, what do you think your gauge will tell you in this situation?

I think it would tell you that the side with a fouled plug will have a richer A/F ratio telling you to look at that bank first. 

No offense, but this is part of the problem with a lot of people using an "A/F" meter.  You still need to understand how things work.  I'm regularly seeing people make wrong choices because of a number on the "A/F" meter.

You can probably guess what the right answer is now that I made my comment, but I still challenge you to think through what an "A/F" meter is actually measuring, and what happens in fouled plug misfire.