GT6/Vitesse Mk1 Exhaust Manifolds

[Christoph Wintersteiger]

Sadly the exhaust manifold on my GT6 Mk1 has a bad crack that's getting worse every day. I've been looking for a replacement for a while, but so far couldn't find the right one (they are all either badly rusted or cracked). At the moment, there are two on ebay, but they look different from the one on my car:

 

Manifold 1

Manifold 2

 

Both of them seem to have the right part number (306483), but ports 2/3 and 4/5 are not fused like on mine; see e.g., this completed listing: Manifold 3

 

Are the non-fused one simply earlier/later ones and they have kept the part number, or are they "pattern parts" by a different company? Will both of them fit onto my engine?

 

If you have one for sale, do let me know!

 

Thanks!

Christoph

[JohnD]

Christoph,

Rust on a manifold really doesn't matter - they are solid castings and will never fail through corrosion.

 

And Manifold 2  "needs new studs", I presume where it bolts to the down pipe.  They are a sod to replace, so I'd go for M.1.

 

The biggest difference between the six manifolds was when the head changed, from Mk.1, all-ports-in-a-line, to the staggered ports at Mk.2.  John Thomason's Originality book doesn't mention any other Mk.1 differences and shows a 'fused' primary manifold as Mk.1, while my Mk.1 Triumph WSM shows then as separate, so I don't think that is important.

 

John

[thescrapman]

There are definately different versions of the Mk1 manifold. That may relate to big saloons and GT6/Vitesse, but I haven't managed to find a pattern.

 

One version looks "stronger" that others, but that is all I have found.

 

Cheers

[Pete Lewis]

from a design life point i would expect the more solid version to crack due to heat expansion stresses more so than the more open version

 

but thats a drawn down from retired grey matter !!!  Pete

 

other variables could be the diameter of the downpipe ,and its sealing flange   when comparing Mk1 1600 throught to big saloon Mk1 2ltr

 

might all be the same but  I dont have any to measure

 

Pete 

[68vitesse]

I have used both Vitesse and 2000 exhaust manifolds on my MK1 Vitesse 2L but am thinking of changing to stainless steel. I have had several crack both front and rear leg and one had cracks on the engine side,I think they are just getting to old and fatigued.

 

Regards

 

Paul

[Christoph Wintersteiger]

Thanks for all the replies! Makes a lot of sense that rust on manifolds shouldn't be a major problem as long as the studs are ok.

 

Intuitively I would also think that fused-branch manifolds are more prone to cracking, so I'll give the non-fused one a try this time.

 

Paul: since you mention stainless steel - are there SS manifolds of the "normal" shape instead of tubular sports manifolds? I'd be highly interested if such a thing exists!