Fibre washer set for a 276 pre Monobloc carb

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REW
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Fibre washer set for a 276 pre Monobloc carb

Post by REW »

My '51 G3L has a 276 Amal carb and has always run well. A recent spell of poor running resulted in a bit of servicing and eventually lead to discovery of a small lump of rubbery stuff in the float needle region - probably the cause of rough running and petrol here and there. All cleaned up and I decided to buy a new set of fibre washers to finish the job off - Amal branded and in a sealed packet from an online seller (not the club - my order this time was too small).

Straight away I noticed how thin and narrow the fibre washers were compared to the ones I had removed and how slack the fit in some cases was. Nonetheless I fitted them, tightened 'em up and turned on the petrol tap. Drip drip drip of petrol. I tightened further a couple of times as the washers soaked up fuel and presumably softened but damp with petrol the nether parts of the carb remained.

I decided to grasp the nettle and chose the best of my pre-used pre-monobloc washers, noting how much thicker and broader they were despite years of use, nipped things up, tap on and...

Nothing - no drips but a bike that ran well again. I therefore raise a concern over the quality of such simple parts and their blatant inability to the job required. The sealing surfaces are small so any reduction through narrow fibre washers is clearly detrimental plus a thin washer is harder to tighten and compress adequately.

What source/brand of washers for these 276 carb have others used with success?
Ron

1951 Matchless G3L thumping round the Durham Dales.
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dave16mct
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Re: Fibre washer set for a 276 pre Monobloc carb

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Rob Harknett
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Re: Fibre washer set for a 276 pre Monobloc carb

Post by Rob Harknett »

The Amal washers are thin Ron. Thin between inner and outer dia. I have not used a new Amal set lately. I have found mixed packs of washers hard. There never seems to be the thin washers as used on the carbs. Also no washers the correct dia. I have filed them out to fit. Household tap washers fibre or rubber now seem to be hard and do not always seal. Must be the material they are now made of. Like new petrol tap corks, if left to soak they seal better.
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REW
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Re: Fibre washer set for a 276 pre Monobloc carb

Post by REW »

The pack was an Amal pack Dave though not from that source.

Rob - I agree, buying a bumper mixed pack doesn't help because the carb ones are strange sizes. So what else could one make them out of? Hard cardboard maybe?
Ron

1951 Matchless G3L thumping round the Durham Dales.
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dave16mct
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Re: Fibre washer set for a 276 pre Monobloc carb

Post by dave16mct »

Maybe ask Martin Bratby? He's the expert with old carbs and very helpful. He may have old stock or a better supply.
Dave.
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Janet
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Re: Fibre washer set for a 276 pre Monobloc carb

Post by Janet »

REW wrote:The pack was an Amal pack Dave though not from that source.
Ron, even if you didn't buy the set from Amal, they're Amal washers so you should still have a valid reason for telling them your problem and asking if they know what could possibly be wrong. They are at the head of the supply chain so should have some interest.
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Rob Harknett
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Re: Fibre washer set for a 276 pre Monobloc carb

Post by Rob Harknett »

I have not made any washers Ron. Last time I could not find one for a carb, I used a fine half round file to file the inner dia. to fit.
Here are two common plumbing washers, found in packs at B&Q etc. The narrow rim washer looks like it will be correct for the bottom nut on a mono block carb, but the i / s dia. is too tight. The other washer fits perfect, but has the wider rim. These washers are only about 1/2 the thickness of those multi size packs of washers. As these plumbing washers are to seal water, perhaps being thinner makes them more flexible to seal? The joining faces of the plumbing washers look flat and smooth, unlike some of those multi pack washers that look like they have been thumped out on a platen press leaving ridges. Daft, I made Platten press jigs and had to get the machine operator to test they are OK. Getting correct pressure for a clean cut, was a very fine adjustment. One of the things I was always thinking of doing was to get some gasket sets made for prewar machines. Could have made them for cost of the tooling and material.
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