Technical 128 SL v 128 3P Inlet Manifolds

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Technical 128 SL v 128 3P Inlet Manifolds

Oct 13, 2015
Hello, all.

I recently bought a 128 3P with a 1300 engine. It’s ok but it could really do with a bit more poke. However, I don’t want to do anything major; a carb, extractors and maybe electronic ignition are pretty much the limit.

I’m currently trying to source a 34mm DMTR that I'll get jetted to 25 & 27 mm, and extractors (this is in train and doesn’t look like being a problem). However, I’ve been told that 128 SLs’ intake manifolds are also a good upgrade; they apparently were made for non-US markets and flow better than 3P ones do. Is this so? I have access to one, so if I’m doing the other work, this seems like a no-brainer to do at the same time.

Also, I have a spare inlet manifold from a 1300 X1/9. Might this be a good upgrade instead? I've heard that X1/9 engines were canted over, so the inlet manifolds are different but haven't had this confirmed.

And finally, while I'm at it, where's the 128 3P engine cooling fan relay located? Is it one of the two that's just behind the fuse block, in the cabin?

Please advise.

PS: here’s the car:

Hobart, Tasmania
128 3P and Serie Speciale X1/9 w/ a 1.5, twin IDFs, cam, etc.
(Yes, I know that IDFs shouldn’t work but they do 😀).


Active member
Dec 30, 2010
Dartmoor, Devon
If you can't find 34DMTR - I had a brand new one, cd tell you where it went (UK) as I don't think he planned to use it.