cylinder fin repair

[harry]

Hi everybody,I have to repair a couple of fins on my vintage Sunbeam and wonder if instead of having them brazed on I could us J B Weld  an epoxy / iron mixture which is claimed to work up to 300c on a continuous basis.I have tried to phone them but the number on the web and on the packet is  unobtainable.I notice Frosts catalogue list a cylinder black paint which is fine up to 280c.so it might be possible to us JB Weld has anybody tried? Harry.

[andyw1260]

Hi Harry
           Have used JB weld on my rat bike a Honda cb650. The  Head leaks oil all over the place when the 6mm rocker enclosure bolts go loose and strip the threads also used JB weld on the join of the head and rocker enclosure good results looks ok if you are blind.  
 Great success Jb weld takes heat and metal expansion ok and lasts for as long as you want.  Not sure about fins as there`s not a lot of meat to get going on with, may weld ok but could be fragile to a knock.
  Most HT paints will be ok on a cylinder head, make sure the one you choose has the right finish flat,matt,gloss.    Andy    

[geoffus]

  try page 5 of the classic biker bar  it will work  geoffus

[thunderbird]

harry i have not used jb weld, but if you have an arc welder you can buy special cast iron welding rods i bought some off of ebay recently to repair a triumph thunderbird head it had a some small fins missing i  was able to build up the the damaged areas with weld then file back and shape time consuming but excellent results,they are special rods designed specifically for welding cast iron and are still listed on ebay,hope this helps cheers steve

[Goldy]

I seem to remember from my long past Apprenticeship days that to weld cast iron successfuly you have to warm the component in an oven first. Carryout the welding whilst still warm and then allow to cool slowly.  If you wrap items in tin foil you can warm things in the oven without too much smell but dont get it mixed up with the Sunday roast.

[thunderbird]

I seem to remember from my long past Apprenticeship days that to weld cast iron successfuly you have to warm the component in an oven first. Carryout the welding whilst still warm and then allow to cool slowly.  If you wrap items in tin foil you can warm things in the oven without too much smell but dont get it mixed up with the Sunday roast.

that is correct goldy but with the wonders of modern technoligies these rods can be used to weld cold cast iron they have a nickel core and low melting point and you dont get any problems with the weld cracking on cooling as was a problem in the past.cheers steve

[harry]

Hi, to you all who replied to my enquiry about  cylinder fin repair,first of all thank; you on balance I think I will get some of the special rods and weld the fins back on.Thanks once again Harry.

[harry]

Hi geoffus,many thanks for your message go to page 5 of classic biker bar.Having now had time to read it and in view of the caution expressed about possible cylinder/head distortion caused by the heat of welding and the positive reports on using epoxy I have changed my mind and will use JB weld to put the fins back.Once again many thanks to you and everybody else for their help.Harry.

[Goldy]

thunderbird - thanks fot the info. My BSA A10 build has a piece of fin missing from the head. I bought a scrap head from Newark autojumble and cut out the piece that I needed using an angle grinder. I finished off with a file to get a good fit. Got some cast iron repair rods from ebay and welded into position.  Easy.

[thunderbird]

good to hear you found the info usefull goldy,i was suprised myself how easy these rods are to use, having made repaires to cast iron the old  way in the past these rods make it a lot easier and its a cost effective way of doing the repair.cheers steve

[harry]

Hi everybody,down at the club last week I mentioned the missing fin problem to a friend who is a very skilled engineer and he said he would braze them on for me.He was of the opinion the a max temperature of 300c for the bond on the cylinder head was probably too low .Anyway they will be fixed for me for the price of a drink{or two}so I am a happy guy.Happy Christmas to you all.Harry.

[HelenJames]

The similar subject was already observed somewhere at this thread