I need to tap the forum's members extensive experience in cunningly convincing better equiped third parties to lend a hand in a project.
Years ago I fitted an autojumble-bought sport exhaust to my Giardiniera, and over time this item has broken and been welded more times than I have fingers to count on. I've just ordered a new one from Axel Gerstl, they acknowledge it's a problem and advise buyers to anneal the exhaust before use.
That means I'll need to go lurking around places of business susceptible to operate an 800° oven that can accomodate a 60 x 20 x 30 cm object.
I have no idea what kind of trade would use such an oven, do you ?
Thanks for your suggestions

I would think that it is more a case of a stress relief job on the pipe bends rather than the entire exhaust. Could be done with a decent blow torch I imagine.

Toshi 975 said:

I would think that it is more a case of a stress relief job on the pipe bends rather than the entire exhaust. Could be done with a decent blow torch I imagine.

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The problem may be more acute on the Giardiniera, the header pipes being much shorter. The breaks I mentionned happened all over, flanges to pipes, pipes to silencer, steady plates to silencer.
I'm just not sure point by point annealing would do the job (?).
The strange bit is that the original exhaust never broke.

It helps to fit the exhaust in the correct order of tightening. Fit it loosely to the elbows, elbows loosely to head, all gaskets in place and sitting in the support brackets with the top clamping part and all nuts started on the threads. Tighten the elbows to the exhaust, tighten the support bracket to the crankcase on all four studs, tighten the two setscrews that clamp the silencer and finally, tighten the elbows to the head.

But, but, but, 800C will likely ruin the paint finish

AL.

800C. Hmmm.
I wonder what type of packing (if any) is used in the silencer and will it stand up to 800C. (I can't remember how hot a short exhaust system will run at). Also, would there be any risk of distortion/misalignment being caused by heating the entire exhaust system so hot without it being in a jig?

I wouldn't bother with trying to heat up the entire exhaust system. Surprised that Axel Gerstl is putting the onus on his customers to try to anneal the exhaust he's supplying rather than on his supplier/manufacturer of the exhaust.

As Peter (fiat500) says, best to fit everything loosely first and then tighten up, working away from the engine.

Watch out for parts not lining up correctly - if you have to tighten something in order to pull it into place, then this will put the system under strain and possibly cause problems later on. (Iirc some people had problems with the one piece? exhaust system on the standard 500 not lining up correctly with both little exhaust manifolds (elbows?). Correct as necessary to avoid problems.

When I was being taught to Gas Weld (Oxy-Acetylene), I was told that it was a good idea to gently tap the weld before it cooled in order to stress-relieve it. (idk if this would work with Mig welding -everything seems to be either Migged or Tigged nowadays )

If it was my car, I'd just fit the exhaust without any annealing providing everything went together correctly i.e. without any stress/misalignment.
If it subsequently cracked, then I'd reconsider annealing. As Toshi 975
suggests, it probably would only need to be done on the bends. Plus possibly where the pipe(s) join the silencer box.

AL.

If 'giardini' does decide to find some trade that can heat your exhaust system to 800C., might I suggest (off the top of my head so I'm only guessing!) somewhere that does glass blowing? Or tile/ brick/ pottery/ ceramics firing? (probably lots of others)

AL.

Thanks guys. Good advice, although it must be remembered that the manifolds exit at the top of the head on the G, and the "muffler" part is bolted to the head itself, so not much scope for an elaborate tightening sequence (flanges & two bolts). Hence, the paint finish lasts about 30 min anyway, and no packing either as that would defeat the "sport" idea
Fine print, Axel Gerstl void warranty for cracks on all exhausts and suggest annealing.
My understanding of annealing is heating to cherry red and slow cooling, and I suppose it should take place over the whole assembly simultaneously to relieve the welding stresses.
Ceramics firing oven is probably the right idea, and any wonder it should come from Italy ? Thanks.

P.S. Seems I've confused the Irish flag with the Italian one... shades of green... and mention of ceramics...sorry : )

giardini said:

it must be remembered that the manifolds exit at the top of the head on the G, and the "muffler" part is bolted to the head itself, so not much scope for an elaborate tightening sequence

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I thought there must be some detail differences between the systems. :bang:

I have one spare vertical-type engine on which I can see that a previous owner has heated the top of the bend on the exhaust pipes, probably to a very high temperature using an acetylene flame. My understanding is that, (in the way that Al advises), if you have slight alignment issues, by getting the pipes up to a temperature where they become malleable you can quickly tighten them to the head allowing the tension to pull them into the correct alignment.
I don't think you will find welds or parts failing on the exhaust due to manufacturing stresses, rather they will crack because of stress induced when fitting to the engine.

https://webshop.fiat500126.com/tuning/sport-exhaust-pipes/sport-exhaust-pipe-double-tailspout-chrome

Right Peter, space is too tight in the G setup to wield a torch in situ without risking roasting a host of other things, but I have a leftover head otherwise ruined by an incompetent welder, but good enough to bolt the new exhaust onto and try it your way.
Check the picture linked above, you'll see how compact the system is, there may be an intrinsic design problem to do with vibe frequency in such short header pipes :chin:

Check also the disclaimer underneath : )

giardini said:

P.S. Seems I've confused the Irish flag with the Italian one... shades of green... and mention of ceramics...sorry : )

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No worries! The Irish and Italian flags are very similar. The Irish flag is sometimes also confused with the Indian flag - same colours, just the opposite order....

I did look up the Axel Gerstl website before posting as I'm not familiar with the engine in the Giardiniera engine and see what you mean by short header pipes and also Axel's disclaimer - still, you're fortunate that anyone can still supply an exhaust system to suit.

Just to clarify what I meant by using e.g. a welding torch to get correct alignment of the exhaust to the engine and mounting points. I didn't mean to heat the pipes and tighten to pull things into position as this will leave things still under stress. The correct way is to heat the necessary parts of the system with it removed from the engine and 'overbend' the misaligned part so that when it cools down, it is now in perfect alignment. This way ensures that the system fits without any stress and gives you the best chance of not developing cracks in service. Having said that, I'll assume that the exhaust was constructed in an accurate jig and the Fabricator has done his best to ensure a good fit to the engine.

Your plan to try the exhaust on your spare cyl. head to check fit sounds like a good move.

AL.

The trouble is, Al, the exhaust is nicely made and a very good fit when you bolt it on. However being so short and compact, it becomes extremely hot in use, expansion takes place, and the very short distance between flanges and muffler fixing tabs means that nothing gives... so something must break.
In my motorcycle racing days we used springs to hold headers to head and silencers to pipes, but that only works with spigoted junctions, not flat flanges.
Must think some more, maybe have a look at how Fiat 126 bis guys cope with it, that exhaust looks a bit similar.