Thought about that already. Since the muffler is where it is and the carb has to bolt to the tank. But a carb from a normal push mower has a similar bolt pattern but not angled down. Probably not jetted for this smaller 3.5hp engine.
How would you fix this?
- Thread starter slomo
- Start date
Going to call Permatex and JB Weld. Get expert advice on the best RTV adhesive and something to build up cast aluminum. I like olddiyer's idea of a flat plate with nuts and bolts. Might be doable with some metal whittling.
Need a good adhesive that possibly can be removed if I need to remove the carb later.
slomo
Need a good adhesive that possibly can be removed if I need to remove the carb later.
slomo
- Joined
- Feb 19, 2020
- Threads
- 91
- Messages
- 11,490
Slomo the problem getting the aluminum welding that is torched to work is that the aluminum is oxidize. In order to get it to melt requires more hear than you think to break through the oxidized layer. Most time by the time you time you do the aluminum underneath it is already liquid and just runs out. Tig welding works but even that is tricky on cast aluminum. If you really want to save the engine then get it Tig welded by an experienced aluminum welder.
Personally I never had any good luck with any of the JB Weld products.
Personally I never had any good luck with any of the JB Weld products.
cpurvis
Lawn Addict
- Joined
- Aug 25, 2015
- Threads
- 21
- Messages
- 2,256
Plus, some aluminum alloys are not weldable at all. Those that are weldable have to be welded with shielding gas, whether from a tank or through the electrode. JB Weld is nothing but epoxy with metal powder mixed in. Epoxy does not like heat.
I think the backing plate with the broken off piece fitted into the break (acting as a spacer; no welding or JB Weld needed) is the best bet. Even if it fails, you have damaged nothing.
I think the backing plate with the broken off piece fitted into the break (acting as a spacer; no welding or JB Weld needed) is the best bet. Even if it fails, you have damaged nothing.
bertsmobile1
Lawn Royalty
- Joined
- Nov 29, 2014
- Threads
- 65
- Messages
- 24,995
Lets not get too exoteric here
1) it is an aluminium die casting alloy
So it will be either 12% Si or 7% Si + 4 % Cu.
A very weldable alloy
All Aluminium alloys are weldable, some are just a bit more difficult to weld than others
When you gas weld aluminium you dip stitch weld where when you see the top oxide start to float you dip the rod through the oxide then pull out, move a little further forward & repeat.
It is dead easy to do if you can get the right goggles that kill off the orange sodium flare.
Gas welding is actually the easiest to do because you do not have to clean the surface and if the casting is porous and full of oil like an engine crankcase the weld puddle will just lift the oil to the surface.
Electric welding of the same object will cause the oil to vapourise and blow molten aluminium everywhere .
Also aluminium oxide, like all metal oxides is an electrical resistor so it is hard to get a consistant arc which is why mig welders use an AC arc or square wave DC arc
Tig is better than mig on a casting because you end up with less thermal cracking and have a lot better control of the puddle size & heat .
I gas weld all aluminium and have no problems what so ever now that I have some of Kent's (https://www.youtube.com/user/tinmantech) lenses so I can see.
I also use a Dillon low pressure torch, now called DHC 2000 which I bought back in the 70's from Mr Dillion.
1) it is an aluminium die casting alloy
So it will be either 12% Si or 7% Si + 4 % Cu.
A very weldable alloy
All Aluminium alloys are weldable, some are just a bit more difficult to weld than others
When you gas weld aluminium you dip stitch weld where when you see the top oxide start to float you dip the rod through the oxide then pull out, move a little further forward & repeat.
It is dead easy to do if you can get the right goggles that kill off the orange sodium flare.
Gas welding is actually the easiest to do because you do not have to clean the surface and if the casting is porous and full of oil like an engine crankcase the weld puddle will just lift the oil to the surface.
Electric welding of the same object will cause the oil to vapourise and blow molten aluminium everywhere .
Also aluminium oxide, like all metal oxides is an electrical resistor so it is hard to get a consistant arc which is why mig welders use an AC arc or square wave DC arc
Tig is better than mig on a casting because you end up with less thermal cracking and have a lot better control of the puddle size & heat .
I gas weld all aluminium and have no problems what so ever now that I have some of Kent's (https://www.youtube.com/user/tinmantech) lenses so I can see.
I also use a Dillon low pressure torch, now called DHC 2000 which I bought back in the 70's from Mr Dillion.
I held a 3650F propane torch to it for a full 2 minutes. Wasn't hot enough. That block just sucked the heat away like all get out.
I used a stainless wire brush on it. Sprayed carb cleaner to degrease it. The flame should of burnt off anything left. Guess I need a larger torch to throw more BTU's. Normal small propane torch didn't have enough beans.
slomo
I used a stainless wire brush on it. Sprayed carb cleaner to degrease it. The flame should of burnt off anything left. Guess I need a larger torch to throw more BTU's. Normal small propane torch didn't have enough beans.
slomo
- Joined
- Sep 24, 2017
- Threads
- 266
- Messages
- 6,633
bertsmobile1
Lawn Royalty
- Joined
- Nov 29, 2014
- Threads
- 65
- Messages
- 24,995
Preheat on that would need to be around 10 minutes minimum with the biggest burner you can lay your hands on.
I use an air:acetylene preheat torch.
I think you lot call them rose bud torches
You need to get the block to around 200 C before you think about building up or welding the broken bit back in
With that particular job probably would do a TIG if I could hold the broken bit in place good enough after the preheat.
Engineering shops sell thermal crayons that change colour which work really well for the pre heat .
If you are not a reasonable aluminium welder then take it to Wally the Welder with a bottle of his favourite booze .
Or if it is a learning process, then carry on.
When I first tried to weld aluminium I had a set of cobalt blue lenses but could never see the weld pool clear enough.
Then I got given one of Kents lenses and since then there has been no stopping me .
I got a couple of Kohlers with the famous crack and after blowing a few holes got them down pat.
Probably done 1/2 dozen of them
I like to do things in batched so there is a pile of cases with vent holes in the side where the counter weight has gone through.
Last run I did about 20 of them.
Kent does a line of low pressure torches aw well that are a fair bit cheaper than the DHC 2000, but I am used to it now so have no intention of changing.
The other nic thing with these types of guns is you can literally weld rust so they are magic on pressed decks, if not a bit on the slow side .
Gord Baker
Well-Known Member
- Joined
- Aug 21, 2018
- Threads
- 1
- Messages
- 394
What OldDiyer said!
I'd like to know what the heavy object was. I would try fitting that piece that broke off back in place, then super-glue it to stay there. Then I would drill and tap (looking at this pic, I would be coming in from the right, with 6 - 10 small holes and screw it together. At that point the mounting hole, if damaged can be drilled and tapped. I just don't know if this engine is worth it.