matt_gsxr
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| posted on 1/2/11 at 12:20 AM |
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Weld the collector first
The saga of my exhaust manifold continues.
Welding thick turbo flange to pipes worked out fine in the end with the MIG. The trick was to do it on the inside of the flange rather than the
outside. Then use the angle grinder as a crude way of machining it all flat. Worked rather well.
So, I was feeling pretty cocky. All welded up and just a couple of small holes where pipes all meet. I tried to get someone to TIG them but TIGers
in Oxfordshire seem to be a bit thin on the ground, so I decided to MIG around the outside to seal it, big mistake. I started with the manifold
bolted to an old head, but as time went on I couldn't get the right access. No problem take it off the head and pop it into the vice.
So, after my usual mix of burning holes, splattering, fires and all the stuff that I call welding I was done. Not pretty but it sealed. Great stuff,
then I went to bolt it up to the head. It had moved like you wouldn't believe (well you lot probably would as you know this stuff). Nothing
lined up.
Bugger, bugger, bugger. Its a short manifold so can't be straightened even with extreme brute force. I think its only fit for the scrap
bin.
So, WELD THE COLLECTOR FIRST when making manifolds.
Tomorrow I buy more pipe and more wire and more gas more cutting disks then I cut off the flanges and start again.
At least I am learning (and welding is the best).
Matt
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blakep82
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| posted on 1/2/11 at 12:28 AM |
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can't you cut some of the pipes most of the way through with the grinder, bend the pipe in the right direction, and then weld them back shut?
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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matt_gsxr
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| posted on 1/2/11 at 12:38 AM |
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maybe, not sure.
I will reassess in the morning. Bit tired and annoyed at the moment.
I guess I could bodge it to get me on the road, and then build a new one at a later date.
To be honest this was my first crack at welding, and I would make a much nicer job if I started again.
Not sure what to do. Tomorrow is another day (except it is today already!)
Thanks for the moral support.
Matt
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James
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| posted on 1/2/11 at 01:31 AM |
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What about getting the 'face' of the manifold machined flat now. Would that fix the problem?
Cheers,
James
------------------------------------------------------------------------------------------------------------
"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights."
- Muhammad Ali
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matt_gsxr
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| posted on 1/2/11 at 08:31 AM |
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James,
Not that kind. Its a bike manifold to the ends have their own individual clamps.
I think I will have a try at cutting and straightening, with the plan to remake in the long term (next winter perhaps).
My car has been off the road for a while now and I need to get it running again before my enthusiasm lags.
Matt
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907
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| posted on 1/2/11 at 09:02 AM |
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Hi Matt,
IMHO when making a manifold the first thing to make is a plate, angle, or length of PFC
that is drilled to the same bolt patten as the head. Heavy enough to stay straight, but
light enough to be able to move around when welding the manifold up.
( I also drill 4 little holes, one in each face, to allow the argon out when purging. )
Example below.
Cheers,
Paul G
 
1600 cf jig
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NS Dev
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| posted on 1/2/11 at 09:11 AM |
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re. the collectors, yep, always make them first!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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matt_gsxr
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| posted on 1/2/11 at 09:12 AM |
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Thanks Paul wise words as ever.
We are coming at this problem from opposite ends, you are an expert metalworker and can weld in your sleep, I just bought a welder, use disposable gas
bottles and spend my days working with computers.
I had a spare head, which did a great job of bracing things, before I needed to get at back of the merge. I just did it wrong.
Matt
p.s. the audi is still working well.
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907
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| posted on 1/2/11 at 09:29 AM |
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quote:
Originally posted by matt_gsxr
Thanks Paul wise words as ever.
We are coming at this problem from opposite ends, you are an expert metalworker and can weld in your sleep, I just bought a welder, use disposable gas
bottles and spend my days working with computers.
I had a spare head, which did a great job of bracing things, before I needed to get at back of the merge. I just did it wrong.
Matt
p.s. the audi is still working well.
Love the pic Matt.  Very Droll.
BTW, I can't weld in my sleep. It sets fire to the sheets  ,
and you just had to mention the Audi,  best car I ever had, and probably ever will have.
Cheers,
Paul G
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SPYDER
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| posted on 1/2/11 at 10:54 AM |
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Just a little aside to this thread...
we made our exhaust from titanium so we didn't know what to expect regarding things going out of shape.
We found that the usual problems were virtually non-existent. The four primaries were each constructed from several sections then welded up
separately and didn't change shape at all.
We did use a jig for final assembly and collector fabrication. The collector was made from three main sections, plus some small infill bits. Despite
all the extra weld the whole assembly hardly moved at all when removed from the jig plate.
It could be something to do with relatively low heat conductivity of titanium.
It is a good idea to incorporate a single stiffener across the primaries if your design allows.
If I were you Matt I would knife and fork your "scrap" manifold 'til it fits then wrap it.
Treat it as "temporary" which often leads to it being "permanent"!
Geoff
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matt_gsxr
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| posted on 1/2/11 at 11:06 AM |
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quote:
Originally posted by SPYDER
If I were you Matt I would knife and fork your "scrap" manifold 'til it fits then wrap it.
Treat it as "temporary" which often leads to it being "permanent"!
Geoff
Geoff, I think that is what I will do (even though I don't know what this means)
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blakep82
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| posted on 1/2/11 at 11:35 AM |
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i think he means what i was saying, cut it up, re weld it, them wrap it in exhaust wrap to hide it. thats what i'm doing with mine when i get it
back!
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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SPYDER
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| posted on 1/2/11 at 12:17 PM |
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"Knife and fork it"...
Oft heard Aerospace factory term.
Use whatever resources you have readily at hand in order to achieve an acceptable, though possibly not optimal, result.
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