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Amal 276 pre-Monobloc carb questions

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Amal 276 pre-Monobloc carb questions

Posted by duncan_latchford at September 04. 2012

Investigating poor low speed running on my WD16H i suspected the carb (felt like a blocked pilot jet) and i am pretty sure i have discovered the problem or problems.

<a href="http://tinypic.com?ref=n5hkjm" target="_blank"><img src="http://i45.tinypic.com/n5hkjm.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

 

cracked float chamber.

 

<a href="http://tinypic.com?ref=2r61onc" target="_blank"><img src="http://i49.tinypic.com/2r61onc.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

 

pilot jet hole does not match up to the block? this is my first time taking a Amal apart but i am sure those two holes should line up to the body. 

 

 

Re: Amal 276 pre-Monobloc carb questions

Posted by duncan_latchford at September 04. 2012

also anyone know what code is needed to make images appear on this message board? :(

click the second image link though and you should see the pictures

Re: Amal 276 pre-Monobloc carb questions

Posted by duncan_latchford at September 04. 2012

Re: Amal 276 pre-Monobloc carb questions

Posted by duncan_latchford at September 04. 2012

Re: Amal 276 pre-Monobloc carb questions

Posted by richard_payne at September 04. 2012

Duncan, I don't  think that the float chamber is the cause of your problem as they'll run quite happily with the lid off but obviously it should be replaced. There is not much chance of repairing 'mazac' once it's started to break down like that but a smeer of 'Devcon' or something might help.

Your chamber has a recent plastic float (and needle, I think) but the seat underneath might not be 100% despite that.

I'm pretty sure that you have identified the problem with the jet block. The Norton single should have adjusting screws on the right (sitting on the bike) which means that the small drilling in the jet block should be on the other side.  However, your block looks to be left handed - i.e. it has come from a carb with the pilot adjusting screw on the left hand side. I have one of those here and I think that it came from an A7 or something.

There is a further complication in that the WD16H and Big 4 were pretty well unique in using 276 carbs as the others used the 276R (Revised). The Norton jet block should have a flat at the back with two small holes for the pilot air feed whereas other makes have a large central airway and the 'gusset' on the carb throat is machined away to allow air into the drilling.

Unfortunately, Burlen / Amal don't manufacture 276 (non-R) parts and offer standardised 276s for the Nortons so you won't be able to buy a replacement jet block from them to use with your existing body (assuming it is the correct original). I hassle Amals at least once a year but they have no plans to re-manufacture.

The Norton jet blocks are not easy to find. I've just recently bought one and had it sent over from Australia. I believe that Martyn Bratby can modify the other type so it might be worth having a word with him.

Re: Amal 276 pre-Monobloc carb questions

Posted by duncan_latchford at September 04. 2012

hello richard 

yes you confirmed what i thought it is annoying because the actual carb body is in great condition. this actual carb was reconditioned at surrey cycles this year maybe they mixed up the block with another carb will contact them and see if they can help also i have contacts with a engineering company that makes parts for F1 will have a chat with them too see if they could re drill my block (if that is even possible ?)

this is what my block looks like from the other side are the holes correct?

http://i46.tinypic.com/30bd27m.jpg

Re: Amal 276 pre-Monobloc carb questions

Posted by richard_payne at September 04. 2012

Duncan, you can tell that the jet block has been botched as it has been filed on the other side to give clearance for the tickover / slide adjusting screw. They were originally machined on one side only. There is no excuse for that sort of sloppy modification. Even if it was done years ago, you should have been advised that the part was not lsuitable for your body.

I'd need to see the bellmouth side of the jet block to tell if it's from a Norton carb. What is the number on your carb body as well ? 276/011 or 276/1BE ?

Re: Amal 276 pre mono block carb questions

Posted by richard_payne at September 04. 2012

Duncan, I've been down the carburation desperation route too. There is quite a lengthy thread on the WD M20 forum which I put pictures of the various parts on. You should be able to see the mixing chamber and jet block variations.

 

http://pub37.bravenet.com/forum/static/show.php?usernum=3155626639&frmid=16&msgid=1224504&cmd=show

Re: Amal 276 pre-Monobloc carb questions

Posted by duncan_latchford at September 04. 2012

haha that is so weird i was just reading that exact page 

it does seem i have a norton 276 body but the 276R block and a LH one to boot!

to get it working i think i can redrill the pilot hole to the correct side and silver solder the old hole which should at least get it running somewhere close to being right. 

what other carbs could be fitted that would still look period? i notice there are pretty much zero 1" clamp mount carbs out there most are flange types 

Re: Amal 276 pre-Monobloc carb questions

Posted by richard_payne at September 04. 2012

The clamp fitting was pretty much a vintage way of doing things. I don' think that many others used them. If you can get hold of a right hand block then that will help. As you'll have read on the M20 forum, several Norton chaps have run 'R' blocks in Norton bodies and say that it works.  I can't see how the pilot air gets down the side of the jet block, although it certainly would if you eased the inlet tract a little on the bottom edge and made the air inlet drilling visible.

You haven't got a lot to lose by attempting to modify the jet block but it is actually three parts soldered together so make sure you don't get it too hot if you decide to have a go.

Martyn Bratby is usually at Netley Marsh. Are you going ? ...I'm just assuming that you're in the UK.

Re: Amal 276 pre-Monobloc carb questions

Posted by duncan_latchford at September 04. 2012

hi richard body number is 276/1BE 

and yh the more i look at this block the more it looks unfit for purpose 

i had not planned to go to Netley Marsh as tbh i don't have the cash to be spending on carb parts atm i think the Amal rebuild will be a long term project on it's own but i have spoken with my cousin today who is going to check the shed so i may get lucky yet :)

i would really like a working carb on this just to confirm the engine is as good as i think it is plus i don't want to risk any damage by running it with bad carb settings. it is super annoying to know you could make it run like a clock on a £20 ebay carb though lol it would look crap though 

yeah i am in the uk in south hertfordshire 

Re: Amal 276 pre-Monobloc carb questions

Posted by duncan_latchford at September 05. 2012

managed to track down a few possible correct jet blocks........... time will tell but fingers are crossed.

had a reply from surrey cycles and apparently they don't recondition carbs just service them, how the incorrect jet block was not reported to the customer is beyond me. just glad it was not my money that was spent there.

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