The 'E' Type Forum

I bought a complete exhaust system, but the downpipes cannot attach to my exhaust manifolds. On the manifolds the studs are sticking out 25-26 mm, and I need at least 35-40 mm to reach the flange and have space for washer and nut. Studs by the way are 3/8", not the ususal 5/16" from other Jags

Are my manifolds not correct? Is the new exhaust system wrong? Is it normal to have to put longer studs in to fit modern exhaust system, stainless (didn't want stainless, but that seems to be the only type available)?
Or?

Thanks, and Merry Christmas

The stud dimensions you give (3/8" and about an inch long) sounds correct.

Thanks abowie, then there must be something else I'm missing, will take manifolds back off and see what I can do. :-)

Put up some photos.

I took the manifold back off to get a closer look. In the first two pictures I've tried to install without any gasket/sealing at all. It wont go further in, I have to cut a bit off the pipe, it's 2mm bigger OD than the exhausts manifold ID. And if I add sealer ring, that you can see on third picture sits below manifold, not inside, there's no way studs are long enough.

So do I need to cut the pipe, remove 5-10mm, and get another much thinner sealer ring? Or?

The sealer ring fits over the pipe which then slips inside the manifold. ( not outside).
The inside of the manifold is shaped to accept the profile of the ring.

Do you have the correct manifolds? I think but don’t know that manifolds from the XK series used a different sealing system. Outwardly the manifolds looked similar but are not correct.

Not sure your new downpipe is compatible with the manifold. On original pipes, from memory, the flange is pretty much the same as on the manifold. The sealing doughnut sits snugly in the recess in both the manifold flange and exhaust downpipe flange. I apply a good smear of sealant paste, bring the two flanges together, fit washers and then brass nuts to the studs and tighten to squish the doughnut into the recesses forming the seal. That simply does not look possible with the flange arrangement on your downpipe...others may know more though...

tim wood wrote: ↑

Mon Dec 25, 2023 9:54 am

The sealer ring fits over the pipe which then slips inside the manifold. ( not outside).
The inside of the manifold is shaped to accept the profile of the ring.

I reckon the sealer rings are wrong.

They are supposed to be a slip fit into the base of the manifold and get crushed as it seals.

Also. The profile of the end of the manifold looks wrong too. It should slip into the manifold and crush the sealer. It looks like it's too "fat".

Alternatively, you could change the manifold studs for longer ones. I would not do this; removing them is difficult and can crack (and ruin) the manifold.

Might be worth checking if the old sealer ring is still inside the manifold (don’t ask why I am asking.).
Merry Christmas
Daniel

Show us a photo of the manifold open end without the downpipe fitted.
Let have a look at the recess.

Good idea Daniel, that would solve it, but unless it's petrified, or turned into iron, I don't think so, worked on it just now.

Further pictures of manifold and pipe

Hi Mikael,
Hope the thing with pictures works. Here is the manifold of my 4.2 S1 project. Diameters look different to yours. I have to say they came in boxes of and I have not assembled the engine yet.

Those look perfect, mine look too small diameter. Did the diameter change during series 1, maybe from 3.8 to 4.2?

No Quarter wrote: ↑

Mon Dec 25, 2023 4:57 pm

Those look perfect, mine look too small diameter. Did the diameter change during series 1, maybe from 3.8 to 4.2?

I think the manifolds with the small chamfered cut-out are from older, non E Type cars. Early MK2 3.4 and 3.8 for example.

The pics Jaguar12 have put up are correct for the E type.

Your options are to modify the downpipe end, fit longer studs (see my previous comments) or get correct manifolds.

Of the 3, shortening the end of the downpipe so you have just enough of a shoulder to support the sealing ring and are able to fit bolts onto the studs is probably the easiest solution. You could also relieve the front pipe square flange by a few mm to give you a bit more thread.

What a PITA.

abowie, I think you're right. A PITA, and yet another part in this car where the original seller 20 years ago just threw something in (deliberate or not) that looked right but wasn't. This project has been a jigsaw puzzle with wrong pieces. Thankfully the price was good...

I'm leaning to buying new manifolds despite cost. I do not want any exhaust leaks to listen to. If I order C18396/C18397, I will get the ones with "the big hole" that Jaguar12 show?

On that subject, I've read that spending the extra € to get them nice enameled or similar, is a waste of money, after hot/cold cycles they'll look bad regardless?

No Quarter wrote: ↑

Tue Dec 26, 2023 5:06 am

On that subject, I've read that spending the extra € to get them nice enameled or similar, is a waste of money, after hot/cold cycles they'll look bad regardless?

Personally I'd buy the unenameled ones and paint them with stove paint, but that's just me.

I don't have any personal experience with modern enameled manifolds but I agree from the forums it seems like the enamel isn't very robust.

SNGB do 3 choices, enamelled, unenamelled and a stove painted i think

Get some new manifolds and new stainless studs - the ones in the pic look well corroded .

Agree....the one in the picture does look a bit tired. Incidentally I spray paint mine with high temp exhaust paint (sperex) dries to a grey-black. Looks fine. Lasts maybe 3 years. A rattle can of paint costs less than £20! Much cheaper than re-enamel coating or the other fancy ceramic coatings which I suspect don't last long on an old cast iron manifold anyway!....back to smashing them Xmas bulbs for me...oh no...they are gone already

I have removed the stock manifolds on my 1965 FHC so will be selling them if any use.
Alasdair