factory 2 into 1 exhaust pipes; left versus right

[HEN3946]

Hi all; I am restoring my 1971 RHD S3 coupe; I have installed the standard exhaust manifolds (the 3 into 1s) and about to add the lower parts - 2 into 1s. Visually these look identical and I cannot see any identifying numbers on the pieces; however the parts book has these listed as RH and LH. Does any one know a) does it matter if these are reversed b) how can you tell the difference between them if it doe matter? thanks

[dxke38]

Hi. I had the same problem after overhauling my engine from my ser 3. I fitted the 2 into 1 down pipes thinking they were the same but when I tried to fit the engine back into the car I found the pipes stood out too far, swapped them round and problem solved. If you loosely fit them you will be able to tell the difference.

[HEN3946]

thanks for the reply; I installed the 2 into 1's after the engine was installed and they seemed interchangeable. As yet I have not installed a new exhaust system so that might be the moment of truth whether I have lucked out and got them the right way around.

[lowact]

Just for the record, here is pic showing the difference:

On my car the straight one is on the RHS, the bent one is on the LHS, it moves the exhaust closer to the engine. If you had them the other way around the exhausts would be a lot further apart (twice the offset), maybe cross pipe wouldn't fit (i don't have one).

[panamacarrera]

Mmm... that might explain my problem... the exhaust ends of my 2 into 1’s didn’t match up to the exhaust... my engine builder had replaced two exhaust manifolds and I put the problem down to them being bad castings. Not having the time or patience to take the engine out again I made up a longer balancer pipe.

Next time I take the engine out I’ll have a look at the 2 into 1 sections.

Cheers

Nigel

[MarekH]

Here are some pictures I meant to post a while ago. They are taken with the manifold ends held against each other square to each other. The effect of mixing them up is that the 2-1 pipes either hug the block or they point outwards toward the frame a bit. Mixed up, you don't have enough space to put a socket extension between the frame and the 2-1 pipes to reach the outer studs, thus making it harder to undo the nuts on the studs.
kind regards
Marek