Jump to content

What is the best option? Okay! Second best option?


Manish Chandrayan
 Share

Recommended Posts

Advert


Just had a look at your album Manish.....

Ooooo dear....crook

Worth trying some epoxy IMHO.....make sure all is clean & de-greased first. I have to say I think the epoxy joint will fail in time however.....

Could you fashion a bracket from aluminium sheet that could be attached elsewhere on the engine perhaps? I'm not familiar with that engine so not sure what fixing points might be available

Link to comment
Share on other sites

Thanks Gents for taking the time and trouble to look up the album.
JB Weld or Devcon Titanium putty is what I have been thinking to try out.
The bracket that broke is what ensures that the carb throat is aligned and seated in the intake. Therefore don't think some other fixing point may not work out

Edited By Manish Chandrayan on 11/02/2018 18:24:51

Link to comment
Share on other sites

the only thing i would try is this stuff ALUMINIUM BRAZING SOLDER . take the carb off and clean all grease oil off around the bracket thats snaped off , just make shur you heat the metal up correctly which will melt the rod and do not melt the rod with the tourch flame.. used it my self on other things and it does work.  Jb weld and epoxy just won't do it

Edited By flight1 on 11/02/2018 18:42:42

Link to comment
Share on other sites

Aluminium engine head repairers/alloy wheel repairer

Would run a localised inert gas, or electric weld on that bit

As only a small amount of metal held it in place originally

A lot of 4 strokes run on an additional interference fit extended manifold

Add a pipe between the two, and brace the carb

 

Edited By Denis Watkins on 11/02/2018 18:59:20

Link to comment
Share on other sites

Posted by Manish Chandrayan on 11/02/2018 18:49:36:
The Aluminum solder/weld had occurred to me but I discounted that due to risk of case distortion.

take the stuff manifold off too before the rest gets quite hot is use, so distortion should't be a concern at 300deg c rod melting piont

Link to comment
Share on other sites

Don't think bush carpentry is a good idea.

There are specialised welding services around that have the ability and tools/materials to effect a proper repair.

I have used Blakers Specialised Welders (in West Sussex) many times and they have done unbelievably good work on in some cases 90 year old aluminium castings. No connection.

Link to comment
Share on other sites

The solder I used to fix a crack in a pipe melts at 235 degrees C. 450 degrees F. But it has to be really clean. I would not use an adhesive I would not trust it especially on a carb and on an engine of that value. Maybe you could make a bracket of your own to fix it to, coming of a nearby bolt the cylinder bolts look close. If using solder or a welder it will get very hot normal outside cylinder temp is I think 245F. So you would probably be best stripping it down and getting the oil and grease and any parts that will melt off it. Apart from that the only thing I can think of before I would spend the money for a case would be to try and fit twin carbs from a Laser 1.60 as it will run better and no need to worry about the same problem happening again. But again that will take some work also.

Link to comment
Share on other sites

Just looking at the last picture on the thread Manish you can see 2 bolts. I don't know what tools you have and what you would be comfortable doing but if I wanted to fix that in as simple a way as possible without trusting an adhesive or using molten metal then a purely mechanical fix would be to make a bracket. You could use the 2 bolts that hold the plenum if that is what it's called behind the carb to bolt in a plate you could make out of aluminium plate basically a rectangular plate with 2 holes in one end for the plenum end then 2 holes at the other end for the carb. You could then use an adhesive to glue a small piece from the carb end to the case as a support rather than a structural joint. I am not sure how heavy your carb is and how much G force you put on the airframe but that is the simplest way I can think of.

You would probably need 2 bolts slightly longer than the original plenum bolts to make up for the thickness of the plate. Maybe a dremmel bit for grinding as the plenum part has a curve in between the bolts and some adhesive that will bond metal well if it needs the support at the end and of course an aluminium plate a back saw and a drill also maybe those nuts with the plastic in them for the 2 carb bolts. But you would not need to take the engine apart which is nice. And it is pretty simple to do.

Link to comment
Share on other sites

TattanMac sounds like he may have a simple/cheap solution that is worth a try. I would not attempt JB Weld etc myself as I cannot see it being successful. If a professional welder can guarantee his repair and it doesn't cost more than half the cost of a new crankcase, then that might be worth a try. Otherwise bite the bullet and buy a new crankcase from JE and put it down to experience - it is a lot but still less than a quarter of the cost of a new engine and your engine won't run as it is!

Link to comment
Share on other sites

Tartanmac

Having reread your suggestion, I think that bracket idea should be doable. Will fabricate one in brass first to see if it works. If it does I will get one made in steel. That bracket along with the original piece glued in should hold the carb good enough.

The engine is (or was) on a Cub so would not experience much of G forces, and the engine being an even twin has advantage of very low vibrations.

Link to comment
Share on other sites

I bought some JB Weld to experiment with rather than getting into proper welding/brazing for a small job. I bonded a length of 1/2" dia aluminium tube to a sheet of 1/8" ali plate (drilled to suit) with JB Weld and was very impressed with the result.

The 'weld' is stronger than the materials being joined and I can't break the pieces apart without bending either.

Only tips I'd give, if you haven't used it before, is to make sure the surfaces to be joined are absolutely clean and free of oil/grease - lightly key mating surfaces if possible and build up as much of a fillet of the weld as is practical.

The joint strength increases markedly with time, so leave for at least a week at room temperature to cure fully, in fact as long as possible.

Link to comment
Share on other sites

Welding the case is hit and miss due to the rubbish alloy used in manufacture.  Techno weld would work ok but be very careful with heat application as any part that gets too hot might cause distortion,sagging or bubbling in the casting.Try the JB weld and then buy a new case  if and when it fails . Check carefully that the impact hasn't cracked or distorted the case. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...