Exhaust manifold question Mk2

[YMJ]

Hi,
this is much more basic...
has anyone welded a lambda boss (mild steel) into a standard Mk1 850 inlet/exhaust manifold?
The point being that the exhaust part of this manifold is cast and the boss will be mild steel.
And if successful, which dissimilar rod did they use? Cast or mild steel?
Cheers

[CooperTune]

I have been adding O2 bungs since buying a gauge. I have my exhaust guy install in the collector or tube just past the bend if no collector. I have been using the late injected cast iron LCB manifolds with Maniflow down popes. These have O2 opening but have to be opened up to accept wide band O2. They also don't work well with pre A+ blocks. I did mount one on a Cooper S block, but it required a lot of grinding on block. Over the years I have had every cast iron welding system demonstrated and yet to buy one. I will ask my exhaust guy about brazing common steel to cast. Steve (CTR)

[BAD942B]

I would have thought that the boss should be in the front pipe around 3 or4" from the y or tri joint, not in the manifold itself which will crack very easily.
If you do put it in the manifold use Tig rod Siphosperbronze no 8 https://migtigarc.co.uk/sifphosphor-bro ... 4429-p.asp which i think is suitable but its a very long time since I read the spec sheets
Those people suggest brazing with Sifbronze no. 1 which you would most probably get off ebay, the answer is to preheat the entire manifold & cool it down over 2 or 3 hrs

[Normal bloke]

I would have thought that the boss should be in the front pipe around 3 or4" from the y or tri joint, not in the manifold itself which will crack very easily.
If you do put it in the manifold use Tig rod Siphosperbronze no 8 https://migtigarc.co.uk/sifphosphor-bro ... 4429-p.asp which i think is suitable but its a very long time since I read the spec sheets
Those people suggest brazing with Sifbronze no. 1 which you would most probably get off ebay, the answer is to preheat the entire manifold & cool it down over 2 or 3 hrs

Thanks. That’s the sort of information I was looking for

[Normal bloke]

I have been adding O2 bungs since buying a gauge. I have my exhaust guy install in the collector or tube just past the bend if no collector. I have been using the late injected cast iron LCB manifolds with Maniflow down popes. These have O2 opening but have to be opened up to accept wide band O2. They also don't work well with pre A+ blocks. I did mount one on a Cooper S block, but it required a lot of grinding on block. Over the years I have had every cast iron welding system demonstrated and yet to buy one. I will ask my exhaust guy about brazing common steel to cast. Steve (CTR)

Thank you

[timmy201]

I have an Innovate MTX-L plus O2 sensor in mine. The instructions recommend a minimum of 24 inches from the head ports.

The best spot for mine was down here, mine is a one piece maniflow freeflow manifold which means no leaks up to this point (one downside of using a stock cast manifold is the potential for leaks pre-sensor)

[Spider]

I'd just braze one in to the cast iron manifold - if that's where you wanted to put it, but check the sensor specs first as some don't like that kind of heat and are fitted a bit further down the pipe.

[andy1071]

I agree with the comments here.. I wouldn't put it in the manifold.

Position it lower down on the downpipe, or after it turns under the floor.
-Yes, there is always the risk of an air-leak between the head and the sensor, but positioned further away, you will be measuring an 'average' of all the cylinders together...