If you`ve used a larger bolt, you`ve probably B_______d it up for a helicoil.
Float Level 276's
- Thread starter rfriedman
- Start date
If the threads are badly buggered..then the material can be welded ...it is a lead/zinc casting alloy - same stuff as modern carbs, fridge door handles and the like...very low melting temperature, soft/large flame..and a skilled welder - gas, not tig or mig
There are all sorts of aluminum/potmetal low temperature welding (brazing? soldering?) rods available on the net. The original was Lumiweld, but it has many imitators and knock-offs now. On a small item like a carb you can do it using a propane gas torch, though Mapp gas if available is quicker. Bigger stuff need oxy-actylene
I've had really good luck with the stuff. It's only flaw is it turns zinc gray, which may be a problem with aluminum but not on standard carburettor bodies.
BTW you can actually put a bolt in a stripped hole, then dribble this stuff in, then remove the bolt after it cools, and have a perfectly threaded hole, since it will stick to aluminum or pot metal, but not steel.
I've had really good luck with the stuff. It's only flaw is it turns zinc gray, which may be a problem with aluminum but not on standard carburettor bodies.
BTW you can actually put a bolt in a stripped hole, then dribble this stuff in, then remove the bolt after it cools, and have a perfectly threaded hole, since it will stick to aluminum or pot metal, but not steel.
Larger bolt but sloppy, not destroying more thread
The throttle stop thread in the body really isnt any worse now than it was when I found it, trev, the bolt's very sloppy.
I had the carburettors 'renovated' by Amal, but they didnt deal with this - even though they charged a vast sum, £12.30, - (well it was a fortune in 1974.)
It's been a long rebuild - but now she runs like a twin rather than a Comet -and back on the road after the last owner took her to pieces in 1964.
Reading the other two posts: Collinsbob, Vapide, many thanks for your suggestion(s): it sounds worth trying the 'low temperature weld' method than a Helicoil.
Many thanks (unless someone in the UK knows a source for the materials mentioned)
wld '50
The throttle stop thread in the body really isnt any worse now than it was when I found it, trev, the bolt's very sloppy.
I had the carburettors 'renovated' by Amal, but they didnt deal with this - even though they charged a vast sum, £12.30, - (well it was a fortune in 1974.)
It's been a long rebuild - but now she runs like a twin rather than a Comet -and back on the road after the last owner took her to pieces in 1964.
Reading the other two posts: Collinsbob, Vapide, many thanks for your suggestion(s): it sounds worth trying the 'low temperature weld' method than a Helicoil.
Many thanks (unless someone in the UK knows a source for the materials mentioned)
wld '50
Possibly expensive blobs on carpet
Got it!
I found this fifteen year old link by someone who had obviously tried Lumiweld with limited success.
[FONT="]http://www.users.globalnet.co.uk/~pattle/nacc/arc0151.htm[/FONT]
[FONT="]"This year's Vincent Club 'Riders Rally' was to be held quite near to my home and even by my lethargic standards it was time to fix the problem and put it back on the road in order to attend. With nothing much to lose I decided to attack the bits with 'Lumiweld' the low temperature aluminium welding stick which is widely advertised (and copied). I don't know what alloys cyclemotor carbs are made of, but it looks more aluminium based than the bigger Amals whose zinc-based material can be welded by Lumiweld experts but turn rapidly into blobs-on-the-carpet for the rest of us. I had one successful job behind me - look at the ally hinge on xxx next time you see it, repaired in desperation when it cracked in half some years ago - it isn't a flush and invisible joint but it has held. Smaller jobs are actually harder, and differences in section between the parts to join also make life harder as they do with all forms of welding, because the lighter item melts before the heavier one gets hot. [/FONT]"
wld '50
Got it!
I found this fifteen year old link by someone who had obviously tried Lumiweld with limited success.
[FONT="]http://www.users.globalnet.co.uk/~pattle/nacc/arc0151.htm[/FONT]
[FONT="]"This year's Vincent Club 'Riders Rally' was to be held quite near to my home and even by my lethargic standards it was time to fix the problem and put it back on the road in order to attend. With nothing much to lose I decided to attack the bits with 'Lumiweld' the low temperature aluminium welding stick which is widely advertised (and copied). I don't know what alloys cyclemotor carbs are made of, but it looks more aluminium based than the bigger Amals whose zinc-based material can be welded by Lumiweld experts but turn rapidly into blobs-on-the-carpet for the rest of us. I had one successful job behind me - look at the ally hinge on xxx next time you see it, repaired in desperation when it cracked in half some years ago - it isn't a flush and invisible joint but it has held. Smaller jobs are actually harder, and differences in section between the parts to join also make life harder as they do with all forms of welding, because the lighter item melts before the heavier one gets hot. [/FONT]"
wld '50
Amal repair
Word of caution on the 'weld repair' solution, the fill metal is usually harder that the parent material so when re-drilling and tapping there is a real danger of running off the repair into the softer body. My brother used to be a distributor for Lumiweld we did quite a few trials of different repairs and thin, zine rich alloys were the worst to work on.
Ian S
Word of caution on the 'weld repair' solution, the fill metal is usually harder that the parent material so when re-drilling and tapping there is a real danger of running off the repair into the softer body. My brother used to be a distributor for Lumiweld we did quite a few trials of different repairs and thin, zine rich alloys were the worst to work on.
Ian S
A method that I have used is to tap the softer metal oversize...then take a coarse thread bolt that fits into that oversize hole....place it in a lathe and drill and tap it to fit the original size bolt..in effect - make your own helicoil..thread the custom insert into the part to be repaired with a healthy glob of loctite and then replace the original bolt...the repair is just as good as the original..and if you use a brass bolt to make your thread insert from - its easy to turn in a lathe..
Trick turning
Bob, that sounds a slick solution. Forgive me, I can do basic macining on a lathe but how on earth do you get hold of such an awkward shape easily and present the work in the correct axis without making elaborate & time consuming jigs? The art of holding awkward shapes would be nice to have.
Bob, that sounds a slick solution. Forgive me, I can do basic macining on a lathe but how on earth do you get hold of such an awkward shape easily and present the work in the correct axis without making elaborate & time consuming jigs? The art of holding awkward shapes would be nice to have.
ok....you don't put the part to be repaired in a lathe..I had to fix my kickstart cover - the threaded hole that takes the clutch adjuster ET27/1AS was partially stripped...so I drilled and tapped it to accept a coarse threaded bolt using hand tools...In this case I used a steel bolt..I then took that bolt and cut the head off..put the bolt part in a lathe - drilled and tapped the bolt - so what I ended up with is essentially a threaded piece of pipe - with threads on the inside as well as the outside...I then cut a small slot on one end with a hacksaw to allow me to insert it into the case with a common slot blade screwdriver..with a dollop of loctite...the threads on the inside are fine thread - retaining the fine adjustment feature of the original.....The only trick I can think of for repairing a carb would be the duplication of the original thread size..and I dare say the repair is stronger than the original..I would use brass as that material has the same, or similar "stiction" as the original alloy...I used steel on my kickstart case because I wanted the insert to resist wear...
