What exhaust is this (I've forgotten...)

[mangocrazy]

Back in the late '80s I bought a 4-2-1 exhaust for my 2 litre Spider, which has been on ever since. I never really needed to give it much thought until I needed to remove the original engine and put in a replacement. Getting the original motor out with the 4-2-1 exhaust was 'challenging' (shalll we say); trying to put the replacement motor back in with it fitted was downright impossible...

After hours of cursing, swearing and trying all sorts of stratagems  to get the exhaust manifold to go past the driveshafts and back water rail with the exhaust still fitted to the rest of the system, I gave up and fired up the angle grinder with a metal cutting wheel attached. Don't worry, I didn't cut the header itself; I cut the main pipe about 5-6 inches back of the joint between header and main pipe.

After  that the engine went in without too much fuss...

I have no idea how I managed to fit the headers in the first case; I can only imagine I drove the car up onto a pair of ramps prior to starting the work. As it stands at the moment, with the car sat on its wheels in the garage in France, I can't believe for a minute that the 4-2-1 will ever be persuaded to get past the driveshafts and water rail. I may be wrong, but...

So my question is (apart from what system do I have) - would it be possible to cut the system at a suitable point and get flanges welded on to permit easier fitment of the system? If so, where should I cut and shut? I've attached a couple of pics of the system; hopefully that should make my question a bit easier to understand.

Also, I've measured the primary and secondary lengths and diameters, and they do seem to be a bit longer than GC's recommended dimensions. Primaries appear to be around 600mm (24") long, while the secondaries are 400mm (16") long. Primary pipe outside diameter is around 38mm, and I've lost the piece of paper with the secondary and tail pipe diameters on it (but can re-measure easily enough).

Would it be more cost effective to get a new two-piece manifold and headers fabricated and sell the current system on, or would it be feasible to cut and shut the current system to make it easier to fit?

[WestonE]

Graham put a pair of flex sections into the 2 straight pipes with twin flanges at the collectors. Both easier to fit and less likely to break or bang on the floor. While you are there get some modern heat waffle heat shield material and make a bolt on heat shield to protect the wiring above and steering rack boots behind.

PS it is a CSC.

Eric
 

[mangocrazy]

Graham put a pair of flex sections into the 2 straight pipes with twin flanges at the collectors. Both easier to fit and less likely to break or bang on the floor. While you are there get some modern heat waffle heat shield material and make a bolt on heat shield to protect the wiring above and steering rack boots behind.

PS it is a CSC.

Eric
 

Excellent advice as usual Eric; to the point and covers all bases. That all makes perfect sense and shouldn't be too difficult to do. Cheers!

[HFStuart]

The only way to fit an engine with a 4-2-1 attached is from underneath with the engine already on the subframe. Even disconnecting it with everything in place is challenging and the car does have to be way up the air to refit - or you need a pit.

You manifold looks very much the same as the ANSA one I used to have  - I'd doesn't look the same as the CSC one I've currently got.

I'm with Eric on the flexis.

[mangocrazy]

Hi Stuart, from painful experience I would have to agree with you...  Time (over 25 years) has obviously blotted out the pain I suffered when fitting it the first time...

[mangocrazy]

I think I've tracked down someone who can make up the flange(s) for me, and I know a couple of excellent welders who can do that part of the job for me, so the next question is where to make the cut on the 4 downpipes. I'm guessing approximately halfway between the rear water rail and the driveshafts would be the best spot; the pipe run is pretty much straight and hopefully that should give enough clearance to bolt the two halves together. Any comments appreciated.

Also I've found this company as a supplier of flexi sections:

http://exhaustpartsuk.com/index.php?main_page=index&cPath=1351

They do clamp-on and weld-on flexi sections - I'm guessing that a weld-on section would be preferable for longevity? Are there any other suppliers of flexi sections that come recommended?

[mangocrazy]

I've finally got most of the needed work done on the Spider exhaust; the flanges have been fabricated and welded on to the (now two-piece) downpipes, flexi sections have been welded onto one end of the twin pipes and the two sections have been sent off to Camcoat in Warrington for ceramic coating inside and out. I just need to get the back end of the exhaust welded onto the free ends of the flexi sections and then spray the back pipe with VHT paint (the whole thing was bead blasted prior to starting the work).

Photos to follow when it's all in one piece and painted.

Only just in time - we're off to France in a week. I have dreams of getting the car mobile again within a calendar year of its demise...

[mangocrazy]

Somewhat later than intended, but here are some photos of the exhaust system chopped about, flanges and flexi sections added and then ceramic coated inside and out and the two into one section towards the back sprayed with VHT paint. The welding is of excellent quality (as always with these guys) and they've thoughtfully welded together the two very adjacent downpipes on both side of the flange to give extra strength.

The flanges themselves are made of 5mm steel plate. I'd originally asked for 10mm plate, but the angle that the downpipes entered and exited the flanges meant that thinner material had to be used. None of the pipes enter the flange 'square', which also accounts for a few small gaps between pipe and flange on the mating faces. All joints are gas-tight though.

On Eric's recommendation I fitted flexi sections on the twin centre section. When I took the two section to be ceramic coated I asked for the flexi sections to be left uncoated, but my instructions were misunderstood it appears. It's no big deal, but it just made welding the back section onto flexi section more difficult. You might notice a slightly different shade of black on the back siamesed section; that's the VHT paint I sprayed on when all the welding was complete.

All flange holes are M6; we reasoned that a number of smaller bolts were better than fewer larger bolts (if you see what I mean. Time will tell, I guess. I'm not intending to use a gasket, just exhaust assembly paste; again this is something that may need revisiting in the light of experience, but I'm trying to keep it simple for now.

Cost overall were less than I expected. The local (Sheffield) engineering firm that fabricated the flanges only charged me £50; I was expecting at least twice that amount and maybe a fair bit more. I will definitely be using them again. Welding was £20 (again, a bargain) and the only expensive part was the ceramic coating (By Camcoat in Warrington). Including return postage, this came to £235.

Anyway, I'm back in France and rapidly running out of time. Hopefully before I return to the UK this weekend I can at least bolt the top section of the manifold onto the cylinder head. Never enough time...

[HFStuart]

Very smart!

I'd be tempted to use that joint plate to brace the exhaust against the block and take some of the stresses off the manifold to head bolts - the flexis can then take care of the movement required

[mangocrazy]

Nice idea, Stuart. I'll investigate that.