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MG MGB GT V8 Factory Originals Technical - Manifold repairs

I'm still looking into modfying standard MGB V8 manifolds to use the good part of the casting and remake the weak part out of stainless. I would therefore need to weld a flange onto the down pipe higher up and have been searching for companies who can do this work.
I've come across a web site that advocates repairing with Silver Solder - something I've never considered.
Have a look at -
http://www.muggyweld.com/silvercast.html
I don't want to start an argument about "how much better tubular headers are and I'm wasting my time" but has anyone any experience of repairing exhausts in such a way ?
It doesn't seem viable to me to repair with silver solder.
Paul Humphries

Paul

Are you REALLY sure??
Merry Christmas

Dave
Dave Wellings

I have a set of OE V-8 manifolds out in my shed, with the usual broken downpipe flanges. I noticed that the flange configuration is the same as that of a 4-cyl. MGB manifold. I would think that it might be possible to cut and dissect the downpipe flanges off of a 4-cyl manifold and graft them onto the V-8 manifolds.

All I need to do is find someone who can weld cast iron.
cheers,
Paul Kile
Paul Kile

Precisely

Happy Christmas
Roger

Welding cast iron is a specialist job but not so difficult that you will have trouble finding someone to do it.
Most welding supply companies will sell you rods for use with a stick welder if you want to try yourself.
Rewelding broken cast iron parts is something which is probably more applicable to pre WWII vehciels were replacements just aren't available. Farming area's will have numerous welders who can do the job. At a recent motorbike show there was a company advertising examples of what can now be repaired when, in the past, it would have been thrown away. My idea of repairing or modifying the original manifolds isn't such a silly idea when you see what the specialist can do.
Paul Humphries

Paul,
Interesting that you mention that cast iron welding is most applicable to pre-WWII stuff that just isn't available. OEM GT V-8 manifolds are just about in that category! I bought a new OE set from Beers of Houghton in 1997 for my factory GT V-8, but the supply is rapidly waning. That's why I figure that repair of broken originals will become more cost effective in the future.

Of course I could always go to RV8 style headers, but I wanted to keep it all original.

Merry Christmas to All!
(BTW, I am going to try making a FIGGY PUDDING this Christmas - see if a Yank can do it correctly!)

Cheers, Paul Kile
Paul Kile

I'm not sure that stainless can be welded to cast iron.
Most successful repairs to cast iron that I've seen were brazed.
George B.

My idea is not to weld stainless to the cast iron but to weld / braze or what ever (after taking to model engineers silver solder seems viable - which surprises me) a new flange just under where all the ports join into the large down pipe, remake the large downpipe in stainless and bolt on.
I'm going to experiment with some old cast iron such as brake discs idc and will let you know how successfull I've been at repairing / welding / brazing at home rather than having a specialist do the job.
Merry Xmas to all.
Paul Humphries

Guys. I have a good 79B shell which needs an engine. Hence, decided to drop down here and lurk for a while. While I know very little about V-8 conversions, I do know quite a bit about silver soldering and brazing. The term "silver soldering" covers several different solders, all containing some percentage of silver. Some, such as the current "plumber's solder" here in the US, are low melting point solders. Not suitable for this type of application, but useful for radiators and such things that do not get hotter than the melting point of about 450 deg F. The "high temperature" silver solders are very similar to brazing rods, but some of them flow (melt and flow into cracks) at a slightly lower temperature. Either a high temp silver solder or a brazing rod may work in this application. The things to remember are that the parts need to be as exact as possible. In other word, the minimal amount of gap possible is the best. Silver solder does not fill gaps very well and the strength of the joint is weakened when there are gaps. Each surface must be perfectly clean and properly fluxed to ensure there will be no problems. Dirt, oil, rust, etc. will make for a weak joint. What the long term effects of this process are, I do not know. In the applications I have use silver soldering (mainly firearms), the parts have held up for many years. If anyone does try this process, I would be interested to know how it worked and how well it holds up over a period of time. Thanks, Les
Les Bengtson

Welding cast iron?

I always heard it was iffy. A friend of mine salvaged a cracked Chevy 350 4-bolt main block. The block was heated then arc welded with a nickel rod. It still seeped coolant after the repair.

These people have a special rod that is supposed to handle the problems of welding cast iron:

http://www.muggyweld.com/4problems.html

http://www.muggyweld.com/cast.html

Worth a try.
Carl

Modern welding of cast iron uses a nickle content rod
(stainless steel) as the filler metal. So, welding of cast iron to stainless steel is a very do-able thing.
However, the expansion rates are very different.
When welding cast iron, the pre-heat and slow cool down is critcal.
Les is right about silver solder's melting point. It's to low for this application. It's great for cast iron but not at the heat level the B puts into a small piece.
I've repaired all types of cast iron over the years. It just takes time to diddle with it. That can cost.

Kelly
Kelly

I spoke to a specialist welder yesterday and anythings possible at a price.
Welding cast iron to cast iron isn't too difficult for him but welding another metal such as mild or stainless steel is expensive due to time and cost of special welding rods.
Paul Hmphries

This thread was discussed between 17/12/2002 and 20/12/2002

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