Setok Posted June 3, 2009 Share Posted June 3, 2009 The guy at the garage that did my Webers and related emissions matters reckoned that I should add some kind of support for the exhaust on my Xflow. According to him the reason it probably ends up blowing through the gasket is that the whole exhaust is pulling down at that point with a fair bit of weight, so supporting it with something would make that problem vanish. Has anyone heard of this being done and does it sound like a reasonable assumption? It's actually amazing he got the blowing to stop. I've never managed to completely do that. --- Kristoffer Lawson Edited by - setok on 3 Jun 2009 19:02:24 Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted June 3, 2009 Share Posted June 3, 2009 This is a big problem when an exhaust is only supported at the head and on the single bobbin at the back. I managed to tear the front plate out of my original silencer. Not sure about on older cars, but there is another threaded bush in the chassis between 800 and 805mm from the centre of the rear mounting hole. Use a small drill to make an exploratory hole in the sideskin, then enlarge it to suit what you find ! This worked fine on mine. The new system I had fitted this year has an additional bracket that bolts to this new hole. In this way, there is no need for any bolts or springs between the primaries and the collector, as there is no downward force. These joints seal nicely. Link to comment Share on other sites More sharing options...
Setok Posted June 3, 2009 Author Share Posted June 3, 2009 As mine is a rear exit there are actually two points at the back that it attaches to, but not likely to make much difference to how it weighs at the front. SM25, what you have sounds interesting. Got any pics of how that works? --- Kristoffer Lawson Link to comment Share on other sites More sharing options...
Jorgen Posted June 3, 2009 Share Posted June 3, 2009 It is unlikely that an old chassis has the extra threaded bush to support the exhaust. According to Arch mine does not have one, it is 1989 vintage. It is normally the center gasket that blows. The seven work shop does a copper laminate gasket that is way better that the standard one. If you dont have that already it well worth the money. Another problem is that the center flange has a tendency to warp sligthly due to the temperature and the fact that the falnge is thin compared to the distance btween the bolts holding it. If you know some body handy at fabricating get a doubble thick flange welded to the exhaust. Those two things cured my exhaust blowing. Cheers Jorgen Link to comment Share on other sites More sharing options...
Setok Posted June 3, 2009 Author Share Posted June 3, 2009 I tried the copper gasket but that was blowing as well. During the 50th anniversary trip we got a temporary solution by using exhaust gasket filler (or whatever that white paste is called), along with the traditional gasket. That worked for a few months before blowing occurred again. Annoyingly I somehow managed to lose the copper gasket in the process. I always wondered why the flange didn't have an extra bolt in the middle, as it's always blowing from there --- Kristoffer Lawson Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted June 3, 2009 Share Posted June 3, 2009 You can just see it here. I can take more pics tomorrow. Link to comment Share on other sites More sharing options...
Setok Posted June 3, 2009 Author Share Posted June 3, 2009 Ahaa! So that's what the wee bracket is for I've seen on some exhausts. --- Kristoffer Lawson Link to comment Share on other sites More sharing options...
Setok Posted June 3, 2009 Author Share Posted June 3, 2009 So has anybody done anything easy for an older car? Mine is a 1989... --- Kristoffer Lawson Link to comment Share on other sites More sharing options...
jonboylaw Posted June 3, 2009 Share Posted June 3, 2009 Hi Kristoffer, I had the same issue until I got the manifold face "lanished" (ground flat), I have seen people make a support bracket for #2 downpipes, I have a photo of one example somewhere. After lanishing, I used a copper Gasket and things seem to work well. Any news on the emissions test ? Jon Link to comment Share on other sites More sharing options...
Setok Posted June 3, 2009 Author Share Posted June 3, 2009 jonboylaw, see my 'garages' thread on ChitChat Basically, emissions done, now the coolant hose broke up! It has been in bad shape for a while, so just a matter of time. And I swear it's not more than 2 years old... Also got a leak on the carb side, apparently (not surprised, really), plus dizzy needs some love (some talk of springs, but as I'm not familiar with the mechanism I don't really know what I should do with it). The poor dizzy also apparently means that it's not possible to properly adjust the timing. I thought with electronic ignition that the dizzy just basically twirled and feeded sparks onwards, but I should probably start a separate thread on that. --- Kristoffer Lawson Link to comment Share on other sites More sharing options...
Gordon C Posted June 3, 2009 Share Posted June 3, 2009 Gaskets that have worked for me (for the siemese pipes) are the ones supplied by Vulcan Engineering. Laminate style gasket....What i can only describe as a asbestos like material, sandwiched between a very thin aluminium outer coating. The inner material what ever it is is designed to have a bit of give and be able to flex thus sealing off those annoying little leaks. Prior to fitting i did smear a little high temp gasket sealer on faying surfaces and thus far i haven't had a trace of a leak yet. iirc these seals are only available from Vulcan so well worth a call. Will say they ain't cheap at about £30 for a set.....but they do work. _________________________ Gordon. Everything in our favour is dead against us. Edited by - Whoosh on 3 Jun 2009 23:07:27 Link to comment Share on other sites More sharing options...
jonboylaw Posted June 3, 2009 Share Posted June 3, 2009 Kristoffer, I have a Dizzy spare, it should be ok, about 12 degrees static, with a fairly new coil and rev limiter if you are interested. Blat mail me if you are interested. I have a colleague coming to Finland on the 16th so may be able to hand carry. Jon Link to comment Share on other sites More sharing options...
Graham Perry Posted June 4, 2009 Share Posted June 4, 2009 I made a set many years ago from a small piece of 2mm thick flexible asbestos sheet that I found. Still use them and no sign of failure or leakage and that is after the exhaust system has been removed many times. Link to comment Share on other sites More sharing options...
Normans_Ghost Posted June 4, 2009 Share Posted June 4, 2009 Kris, I would say that your large centre flange is warped. It matters not how thick the gasket is or what it's made of, if your flange is warped you'll blow. Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here You and your seven toThe French Blatting Company Limited Link to comment Share on other sites More sharing options...
Tony Whitley Posted June 4, 2009 Share Posted June 4, 2009 I love it when you talk dirty, Norm 😬 Link to comment Share on other sites More sharing options...
Graham Sewell Posted June 4, 2009 Share Posted June 4, 2009 Norm, That was exactly the problem that I had with my x-flow. Copper gaskets did not work until I took the car to Chris Wheeler at the 7's workshop and had the manifold mating surfaces ground flat. Since then, it has been fine. Cheers, Graham ------ Low tech luddite - xflow and proud! Link to comment Share on other sites More sharing options...
Setok Posted June 4, 2009 Author Share Posted June 4, 2009 For me it's the cylinder side which is rough, and the likely cause. Still, I'm left wondering if a support mechanism might be possible somehow. I'm pretty sure it's always the center pipes which start blowing, and specifically from the top. So with that in mind a support bracket could very well make sense. --- Kristoffer Lawson Link to comment Share on other sites More sharing options...
Graham Perry Posted June 4, 2009 Share Posted June 4, 2009 In my experience it is usually the tops of the centre pipes as you suggest. Link to comment Share on other sites More sharing options...
jonboylaw Posted June 4, 2009 Share Posted June 4, 2009 Hi Kristoffer, do you have a steel rule you can place against the manifold face to see if it really is flat, what happens is that the warpage means the gasket is not pinched up flat as the two ends where the bolts are, tighten down 1st. This leaves the centre loose and the weight of the pipes pull it down and hence the blow at the top. I would not think that a rough face on the engine side is the problem, more like a bowed manifold, hence my suggestion to get it lanished. Jon Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted June 4, 2009 Share Posted June 4, 2009 ... or 'linished' south of the border. Who knows what it is called in Finland ... probably has loads of a's and i's !!! Link to comment Share on other sites More sharing options...
jonboylaw Posted June 5, 2009 Share Posted June 5, 2009 Ian, My favourite word in Finnish is : saniteettipussi Which means Sanitary Bag 😬 Kristoffer, I just saw this on Ebay: Xflow Manifold plate Something similar may work, need to get your pipes welded to it and would make fitting the primaries through the side skin a pain, but stiffens up the manifold. Just a thought. Jon Link to comment Share on other sites More sharing options...
Setok Posted June 5, 2009 Author Share Posted June 5, 2009 Hm, now that looks interesting. It could spread out the load a bit. I wonder if anyone has tried it? Holes look a bit small, but maybe that's an optical illusion. No idea what 'linished' would be in Finnish, but probably something like 'hiottu'. --- Kristoffer Lawson Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted June 5, 2009 Share Posted June 5, 2009 Not sure what that gasket plate is made from. But, imagine you would still want the faces of the manifold to be flat before fitting it ? Link to comment Share on other sites More sharing options...
jonboylaw Posted June 5, 2009 Share Posted June 5, 2009 Ian, It is Mild Steel, so probably not suitable to welding to Stainless, maybe a useful template to have for making one up in Stainless. IMHO, best to get the current Manifolds "flattened" and use copper gasket set and see how things go. Jon Link to comment Share on other sites More sharing options...
Midnight Posted June 5, 2009 Share Posted June 5, 2009 I had the centre flange on my X -flow replaced with a Van Deiman part which is much thicker at roughly 12mm from face to face and cures the problems with the exhaust blowing caused by the weaker standard version flange bowing over time, with no way to keep it at the head between the siamesed centre pipes. Been going now with one gasket for over 10 years. It was a pleasure to watch the skill of the guy who did the work in Croydon, cut off the old flange and welded on the new one completely gas tight. They apparantly make exhausts for lots of racers including some F1 items, just wish I could remember the company name, as I can't find the invoice after all this time. Link to comment Share on other sites More sharing options...
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