What is part number for 16 MM O2 sensor bung on SSI Heat exchangers

[roadster49]

Hello everyone,

I purchased a new set of think flange SSI heat exchangers for my 1983 911 SC about a year ago and finally bolted them on the car during my rebuild.

They went on just fine.

My Question relates to the O2 Sensor. The original exhaust had an18 MM sensor. The SSI has a16 MM bung. Does anyone know what O2 Sensor fits this. I looked at Bosch and they don't indicate the width.

My engine seems to be running rich based on the carbon I see on the bolt I used to seal the bung. I recently had a backfire that blew up my air-box so I want to get this engine back to original when I finish the rework.

Thank you.
Roadster

[roadster49]

Here is the bung on the SSI

[JJ 911SC]

Originally Posted by roadster49

... I recently had a backfire that blew up my air-box so I want to get this engine back to original when I finish the rework...

You need to instal a Pop Off Valve.

I tough a simple google search would find a lot of 16mm but not...

I'll measure mine to see what size it is.

[The cap'n]

18mm is the industry standard. Either drill and tap it to 18mm (if there's enough metal) or stop by your FLAPS or a better quality muffler shop and buy an 18mm bung.

The Cap'n

[911pcars]

A SS bung is a better match for the SS heat exchangers. Ebay is a good source to see a wide range of bung styles (regular, concave, slant mount, extended, etc.). A welder will have better access if the heat exchanger is on the bench. That could be a big deal if the heat exchangers were on the engine for a long time, but after only a year, shouldn't be a problem. Consider installing a matching bung on the other side in case you eventually want to confirm/tune both sides with a wide band O2 sensor gauge.

Sherwood

[JJ 911SC]

Originally Posted by JJ 911SC

You need to instal a Pop Off Valve.

I tough a simple google search would find a lot of 16mm but not...

I'll measure mine to see what size it is.

As per the cap't, my old one measured 18mm.

Go with Sherwood suggestion and do both sides. I got only one which did not mather when I was "stock" but now I really need the other side to due a proper tunning.

[roadster49]

thanks everyone

Good advice. Will drop both SSIs. cut the 16mm bung and have 18 mm bung welded in. For now plug the passengers side.

So what are the advantages of the wide band? Cost?

I wonder why Dansk put on the 16mm bung

Thanks again

Michael

[Raceboy]

For cutting M18x1.5 thread (which is standard O2 sensor thread), the hole must be 16mm. So no need to cut and weld anything, in fact you should not!

[911pcars]

Originally Posted by Raceboy

For cutting M18x1.5 thread (which is standard O2 sensor thread), the hole must be 16mm. So no need to cut and weld anything, in fact you should not!

IOW, the tip of the sensor should be able to fit into the exhaust tube hole.

[Raceboy]

The biggest sensor tips are on Bosch LSU4's and these measure 15 mm...

[911pcars]

Originally Posted by roadster49

thanks everyone

Good advice. Will drop both SSIs. cut the 16mm bung and have 18 mm bung welded in. For now plug the passengers side.

So what are the advantages of the wide band? Cost?

link to advantages:
WideBandO2Sensor.com - Wideband o2 Frequently Asked Questions (FAQ) - Wideband o2 Frequently Asked Questions (FAQ)

I wonder why Dansk put on the 16mm bung

There are o2 sensors with 16mm threads; some with 12mm threads. Most common size for automobiles is 18mm.

Thanks again

Michael

Hope this helps.
Sherwood