With a 73 with no catalysts, rams horn manifolds and sidepipes, where is a good place to put a bung for a wideband? It would be ideal not to cut a hole in the sidepipes but can the bung go into the manifold itself? I assume it should go on the hotter bank...this true and which is hotter?

 

i think i'd put the bung on the header pipe somewhere just below the "collector". i don't think you need it mounted to the manifold. i'd start with the pass side because you can run the wire(s) on the pass side, have a helper on that side. that way you don't get crossed up with a bunch of wires while trying to drive.

 

Put it in the headpipe on the driver's side just below the flange that bolts the headpipe to the manifold - right above the first bend in the headpipe tube. Done it several times, and it works perfectly. This is also where the early C4 sensors are located for the single-sensor systems.

 

Lars: He said wideband, though. The widebands easily overheat. Narrowbands love heat where widebands hate it.

I had my Bosch LSU4 wideband in the collector and it overheated. I made a heatsink out of a 3x8 sheet of copper and it worked in the collector but I think it was borderline.

 

When I say sidepipes, I mean OEM side pipes...not headers and sidepipes. This means rams horn manifolds bolted directly to the sidepipes/mufflers. Does the same advice still apply? I really hesitate to modify these in any way as they go for big money these days

 

Your in a difficult position, but anything made with exhaust pipe can be repaired to look like original. You need to locate that sensor down stream aways for best results.

 

i'm not sure what the max temp the wideband o2 sensors like, but if i had to guess, the location in my header collector is around maybe 500F-700F (i should measure before posting i know). i'll bet it could get hotter from exhaust gas under certain conditions, but then it gets cooled some being outside the car, air cooled and all.

maybe someone on the forum with the same type sidepipes as yours will shoot some temps and post for you.

zwede & shafrs3 are correct. the LM1, if that is what you have, provides a diagram to make a "heat sink" (i think cooling fin) for the sensor. So consider room for sink when selecting location. follow instructions on location with regard to O2 orientation. Also consider effects of placing right behind wheel as debris could damage and water could cause thermal shock damage.

in your case, after tuning, insert plug into bung. not many would ever notice. as long as you own the car, you can insert o2 and retune anytime. if you sell the car and new owner must have original, a good welder can make that tube look like nothing ever happened as long as it is good metal.

back to your original question; the temperature for every cylinder will be different. if you had headers, you could put a bung and/or o2 sensor in every tube. but this is beyond point of diminishing returns for old street car for most folks. locating in the down tube is a comprimise or average for one side. you could add a bung on both sides which is fine, but i think you'll find that tuning with the wideband, you'll not need to reach that level of accuracy. i have one in each header collector but have only used the pass side so far. once it's about right (whatever that is), maybe i'll check the driver side. i expect the numbers should be so close so as not to require any tuning changes, but it is there. you can always add a bung to the other side later if you suspect you need to check for some reason.
sorry for wordy reply . . .

 

Not trying to hijack the tread here, just looking for a little related info.

Does anyone know how sensitive the Innovate (or other) is to electrical interference? I had the mechanic weld an O2 bung in the exhaust system during the restification, but am concerned that electrial interference would keep an O2 sensor from working.

We run a Mallory box with solid copper core plug wires and non-resistor plugs. Additionally, we only use the top shield ('64).

I have an accelerometer, and even connecting it to its own 12-volt battery, it doesn't function properly due to electrial noise.

Anyone with experience in this area?

Thanks