Hi all this is a place is going to record and document my stainless steel header and collector build .

my methods leverage basic tools and mainly a lot of effort . This first post is really a mass picture upload my reply will go into more detail .

Hand cut 10mm steel flanges . I actually made these in a covid lockdown out of scrap

Old cylinder head for use as a jig makes this project possible

Collector templates

Trimming the ss 304 pieces

Looking for that fit up

Getting a handle on purge tig welding these

Chopped those off


Having a play on the bench setup

Making the port transitions

Seeing how it could look

 

The thread title was locked and wouldn't edit. I had to copy the thread to make your requested title change which has lost the 'likes' for your original. Added mine and I'm sure there'll be more.

Graham

 

Thankyou kindly for fixing that.

Right so some of the details i didn't fully explain the first go around are below

Why mild steel flanges ?
Milling these flat after fabrication is going to be a tricky setup. With my belt sander it will cut the mild steel nicely for a good flat surface. Welding Mild to 304 is common practice using the correct 309L filler wire.

Why the original Downpipe ?
Its more a question of process and the stages to build these headers. Step 1 is to replace the upstream Cats with straight tube and place V-bands connections near the O2 port locations. This is so i can run the original cast manifolds while pouring hours of work into the new headers. Before the cast manifolds get installed its necessary to place a collector on the v-band nice and secure and build a jig to the cylinder head.
Now i have the ability to build the manifolds on the bench. Test fitting often will be necessary a neat feature is that a cast manifold can support the downpipe while i work on the other 3 cylinders and vice versa - a little like the image shown above where I'm holding a collector.

What Design am I going with ?

By far the nicest headers i have found are the Dr Jag ones from Australia, they have a particular tidy balanced look about them and it appears attention has been made to keep the primary lengths as close as possible the way i have constructed my collecters is in line with these.

Next up is the simply performance headers - these look to be the most simple to build , a feature of these is they retain a somewhat standard looking downpipe. For reasons stated above id like to meld this feature with the primary arrangement of the Dr Jag Headers

Last up is the headers i found on this forum - sort of a Rams horn Hi rise design - the collector looks to be the worst of the 3 images shown. The hi rise is kind of cool but i think it will cause heat issues with the rocker cover and or the bonnet.

Dr Jag Headers - note collectors

Simply Performance

Not sure but a member on here had them made i think.

 

There are many topics that mention downpipe modifications but I’ve never actually seen what anyone has done .

You can see the V band flanges added to where the cats were cut off . The catalyst converts actually have a lot of offset in them to account for . Some crafty bends and both are landed

Many test fits to get things sitting right

Old cylinder head for welding jig makes life easy .

 

Not sure if anyone is interested but here goes

My car now has 81,000km
un cracked manifolds

When I sat a straight edge on each once it rocked considerably. The exhaust gaskets were not leaking and no studs had snapped yet. It took quite a lot of work on the belt sander linisher to get the faces to clean up .

for those with not cracked manifolds of an unknown origin It it might be worh it to have yours machined or linished and they might last a lot longer .

This was a very quick first pass , the shiny spot is high and it visually shows how much it pulled . It’s surprising it wasn’t leaking - a credit to the multi layer gaskets .

These need more work , each end still isn’t fully cleaned up after what felt like a long time on my linisher.

 

What kind of shop would have the equipment to resurface ?

 

Any local engine reconditioner would have the correct fly cutter on a milling machine to do a really nice job .

otherwise most reputable workshops would have a guy they send this stuff too for being done .

 

Those would be Hayward and Scott's

https://www.haywardandscott.com/jaguar/xj6.html

Very much vested into your project! I also am searching for a SS exhaust setup. Best of luck!

 

Just for reference, this is how the Scot & Hayward manifold looks like below the headers

 

It’s been a long time since an
update .

I’ve got a couple of runners mocked up in position looking quite tidy . I’m doing my own thing here but as you’d expect it follows a similar path to what others have done

 

This is going off for welding soon , then i need to buy some more mandrel bends to build the other one.

 

Been a while since an update

I have finalized the mockup of the right side manifold , the first runner that goes near the block and the power steering was quite tricky but the placement is now correct. It took a few attempts at getting the collectors to align nicely with the downpipe, I've added a flex bellows to give a little bit of movement between the manifolds and keep things a little bit independent.

The mockup / fitup stage is complete and its time to start the task of purge welding everything.
OE Downpipe, design is nice, has a good heat shield. No reason not to use it again.

Collector placement near the firewall and block

Collector placement near steering

Mockup how it looks and fits

 

That is gorgeous work!

 

it’s been a while since I posted how I’m going with this , need to do some purge welding then it’s onto fitting up the last runners.

 

Glorious work

 

There we go

Fitting up sections is completed. they fit nice on the car. Easy to install and look right at home.

On to the tig welding next.