Author Topic: Amal 276 leaking  (Read 307 times)

Online WozzA

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Amal 276 leaking
« on: 30.05. 2020 01:25 »
I'm still having trouble with the 276 carb leaking, it's leaking from the 2 holes in the carb body,

I believe the needle is ok but still not sealing on the seat... question is how can I get the seat to seal when the float lifts the needle?

I've tried a thin coat of grinding paste on the needle rotated in the seat BUT with no luck...    *rant*

Something I have noticed is my carb does not have a SEATING LOCK NUT #35 as pictured...

How can I remove the seat from the Chamber body? 

Best to ask the experts before I take to it with a engineers hammer..    *warn*
'51 Golden Flash Plunger
'57 Golden Flash Swingarm

Melbourne
The biggest lie I tell myself is
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Offline AdrianJ

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Re: Amal 276 leaking
« Reply #1 on: 30.05. 2020 04:33 »
Not much help but I only managed to fix mine by buying a new JRC carb.
Adrian.
'53 Plunger Flash, Steib S500.


Offline Swarfcut

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Re: Amal 276 leaking
« Reply #2 on: 30.05. 2020 08:33 »
Wozza   If a bottom fed carb, try it with the float chamber top removed. If the valve seals, then the problem is that the needle can't rise enough, and is fouling on something in the guide on the underside of the lid, muck or corrosion, easily removed with a small drill.  Float locates on the needle OK?

    An original needle seating may prove difficult to remove from the float chamber,  the two metals amalgamate to a degree over time. Most folks don't bother and replace the whole thing. Best attack is a little bit of warmth, say half an hour on the barby, on a nice even heat, thick gloves, firm support, good fitting tool. Check availability of the replacement parts before you go to this bother, as in the worst case scenario the valve seat will be damaged and the float chamber crack.

      Grinding paste is far too coarse, Brasso metal polish was the medium of choice, these days try bath cleaner, T Cut or even toothpaste, in other words a very mild abrasive.

 Alternative is to try a different needle first, or another float chamber, but with a used one the same worn valve seat is a risk.

 This is where the Monobloc scores, the float arrangement is a whole lot simpler to service and an improvement on this design.

 Swarfy.


Offline Simon59

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Re: Amal 276 leaking
« Reply #3 on: 30.05. 2020 09:28 »
Similar problem with my 276 carb. I ordered a new needle and plastic float from Amal, plus some new fibre washers, which have literally just arrived in the post. I'll try it today and let you know if it stops the leaks...
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Offline Simon59

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Re: Amal 276 leaking
« Reply #4 on: 30.05. 2020 21:13 »
New float and needle fitted today and new fibre washers too - but my carb still leaks. Drip, drip, drip  *sad2*
Restored a 1954 plunger framed A10 Golden Flash - now finished!

Online Greybeard

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Re: Amal 276 leaking
« Reply #5 on: 30.05. 2020 21:29 »
New float and needle fitted today and new fibre washers too - but my carb still leaks. Drip, drip, drip  *sad2*
The outside of the carb on mine gets 'moist' if the engine is not running and the fuel tap is open. Therefore I don't leave the tap open when the engine is stopped.  *good3*

Offline Simon59

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Re: Amal 276 leaking
« Reply #6 on: 30.05. 2020 21:57 »
Understood Neil. Even though my 276 carb leaks (about one drip a second) it's only when the engine isn't running and when the taps are on. I just thought that I could cure it (I could live with 'moist') but it seems to be beyond me. It doesn't help that my bike sometimes takes quite a few kicks to get started (a different problem?) by which time I've leaked a lot of petrol. 
Restored a 1954 plunger framed A10 Golden Flash - now finished!

Offline Swarfcut

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Re: Amal 276 leaking
« Reply #7 on: 30.05. 2020 22:04 »
 A few of things to consider on 276 carbs with remote bottom fed  float chambers.
   At standstill, the fuel level in the float chamber has to be marginally below the top edge of the jet block. Otherwise fuel will overflow and the needle valve will work perfectly to maintain this  flow. The constant drip is blamed on the needle, but may in fact be due to incorrect assembly.  So make sure all the spacing washers are correct, and the float chamber is in its correct vertical position relative to the carb body to maintain the fuel level just below the top of the jet block.

    There is a thick sealing washer under the jet block, Part 34 on Wozza's parts diagram. This affects the distance relationship between the top of the jet block and the top of the float chamber mounting lug as it in effect positions the mixing chamber union nut (Part 21) relative to the carb body, and consequently the vertical relative position of the float chamber. A missing or too thin a washer will raise the relative fuel level, by raising the float chamber.  Also a thicker washer between the float chamber mounting lug and the base of the nut lowers the relative fuel level, so is an easy first try.

    Also worth altering the float position on the needle, to lower the fuel level, before condemning the needle and its seat. The needle has a groove and clip for location, an old trick was something light and petrol resistant under the clip to move the float down the needle and lower the level as a last ditch fix when all else failed and an expensive replacement loomed.

 As GB says, fuel tap off when parked up.

 The float chamber has to be vertical  whereas the carb may be inclined. Float chambers came in variants with different angled mountings to suit the application. Hope you folks all have the right ones.

 Swarfy.

Online WozzA

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Re: Amal 276 leaking
« Reply #8 on: 01.06. 2020 07:15 »
I THINK I've solved the problem of fuel leaking from the 2 carb body holes...
I've been a bit heavy handed with the tickler, which I'd press like the Monobloc on my '57..
causing it to flood..   *bash*   It seems the 276 only needs a couple of sharp presses...
She even fired up 1st kick & I was able to take her for a quick shake down blast for about a mile or so..
A few minor adjustments to the rear brake & clutch still needed but nothing too serious..
Now she's got just a few weeps from the Banjo nut & float chamber fiber washers to solve..
THANKS Swarfy, your thoughts were a GREAT help.   *wink2*
'51 Golden Flash Plunger
'57 Golden Flash Swingarm

Melbourne
The biggest lie I tell myself is
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Online Rex

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Re: Amal 276 leaking
« Reply #9 on: 01.06. 2020 08:19 »
My Ariel is the same. The rule seems to be petrol on, a couple of pushes on the tickler and then petrol off until the engine's running, then petrol back on again.

Offline dave55

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Re: Amal 276 leaking
« Reply #10 on: 01.06. 2020 09:59 »
Wozza dont forget to soak the fibre washers in oil before using , they compress and seal better .
BSA Bantam D7 175  1961
BSA A10 650 Golden Flash 1955 Plunger
Suzuki GSX1400 2003

Offline Simon59

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Re: Amal 276 leaking
« Reply #11 on: 01.06. 2020 14:48 »
Rex, I think I might have to follow your advice - petrol on, don't over-tickle, petrol off until the engine's running, then petrol back on again.

Yesterday, I followed your suggestion Swarfcut and reduced the height of the float by adding the little clip that Amal supply with their plastic floats, to the groove in a new needle with my brass float. It still leaks like a sieve after about 30 seconds with the taps but the engine not running.

Everything else is checked and fine. So maybe I'll just live with it?   *conf* 
Restored a 1954 plunger framed A10 Golden Flash - now finished!

Offline Swarfcut

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Re: Amal 276 leaking
« Reply #12 on: 01.06. 2020 16:30 »
   Simon, the problem you have is easier to solve by considering the float chamber alone.  The bottom fed needle valve will only close provided the needle can rise unobstructed and be held up by the float. So is the float a good one, not leaking and not with  petrol within or weighed down by soldered repairs?   The old test was to put the brass float in warm water, watch for air bubbles, there's the leak.

    Anything hampering the needle? The best way to test the operation of the float and needle is in isolation. Once established that this part is as it should be, then turn to the source of the oversupply of fuel to the carb, as outlined above in my earlier posts. Wrong fuel level or leaking joints should be an easy fix.

 Best to try and cure somehow, drippy drip onto the magneto is a bit of a no-no.

 Swarfy.

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Re: Amal 276 leaking
« Reply #13 on: 01.06. 2020 19:04 »
Just a think: In this hot weather is it possible that your tank is not breathing and hence pressurising the float valve?

Offline dave55

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Re: Amal 276 leaking
« Reply #14 on: 01.06. 2020 19:24 »
Simon 59, like Swarfy says leak + Mag = Fire.      and it is not a nice experiance to see your nice shiney bike going up in flames whilst running and even with petrol turned off took a while for 2 of us to blow it out   :(
BSA Bantam D7 175  1961
BSA A10 650 Golden Flash 1955 Plunger
Suzuki GSX1400 2003