Can someone tell me where the fuel level should be on a 276 carb please. I've replaced everything in the carb and new float etc, the level as you can see in the picture is about level with the top of the mixture screw. I thought this was where it should be? The problem is the fuel is higher than the bottom nut on the carb and dripping out the hole above the nut. Has anyone any ideas? Thanks.

email (option): horror@blueyonder.co.uk

That looks like a 276 and not a 276R so it doesn't have the overflow on the side; The only place that fuel can go to on a Norton is into the engine or out of the intake.

You should definitely have a long mixing chamber nut on the OHV engine. Don't go believing all that 'book-learning' from Burlen...OHVs with horizontal intakes have long nuts too.

With the short nut, fuel is right on the point of overflowing, even if the float needle seals 100% immediately.

Fuel level should be half-way up the pilot air screw drilling as I understand it - it is on the monobloc anyway.

I realise the fuel will be above the nut so it must be the jet block that is letting the fuel through. There are holes around it at about the hight my fuel level is, so it must be too high.

email (option): horror@blueyonder.co.uk

Sorry Rik, your post wasn't showing when I commented. Ok I'll try a longer nut, thanks.

email (option): horror@blueyonder.co.uk

Carb says 276FT/1DJ

email (option): horror@blueyonder.co.uk

Ok, that seems to have fixed it thanks. This doesn't make sense, it shouldn't matter what the engine is if the level has to be half way up the mixture screw for both. So why is it different for OHV and Side valve engines? I bought this long nut as I have the same problem with my 16H, but it brought the level down loo much, so I wasn't expecting this to work now. I'm thinking I might have got a false reading on the 16H so I'll buy another long nut and do it again. I think this has probably got more to do with worn float chamber making the float sit higher or what is the point of the short nut? When I spoke to Amal I was told the long nut is for angled inlet manifolds and both OHV and side valve had the short nut. But whatever, it's working and that's what counts. Thank for your help.

email (option): horror@blueyonder.co.uk

Dave I think you have a wrong mix of parts. That jet block with the holes is for a 76 carb not a 276. Ron

email (option): ronpier@talk21.com

Ah ok, I bought a couple of jet blocks that were meant to be Norton, marked 30T I thought it was the same as in my carb. I was looking at it to try and work out why the fuel was coming out. I now know they're no good for my 276 carbs. Thanks for the info.

email (option): horror@blueyonder.co.uk

I've assembled two separate carbs for my 16H, both with completely NOS parts (apart from the odd cover etc.) Both over-fuelled with the short mixing chamber union nut. If the fuel level is above the pilot jet then it's going to find its way into the mixing chamber.

You're right though that the same level cannot be correct for both lengths of nut.

I believe it was Martyn Bratby who mentioned the differences and that it was to do with pick-up when opening the throttle smartly. It seems logical that inefficient side-valves have a lower inlet tract depression and are less able to draw mixture up quickly.

The post-war Amal lists show the 276FT/1DJ as being fitted to the 1953/54 Model 18. It used the 6/062 mixing chamber nut and the side-valves continued with the WD-specified 6/033 (which must be the short one).

I have a suspicion that the brass floats bounce up and down a bit and struggle to find their seats when the engine is running, added to which just possibly, modern fuel full of aromatics is less dense than pre-war fuel and float buoyancy may be a little borderline.

In actual fact, bearing in mind that Norton were not making any WD-contracted Model 18s, it would seem quite likely that they had no stock of 1 1/16" 276s and that actually the few WD18s would have used standard civilian Type 76s with the external pilot air holes.

Ok thanks, that makes sense of why the side vales have the short nut. I've changed the float to the nylon type so should be a good as I can get it. I think it's ok now, starts well but haven't ridden it. Got to do the same with the 16H now.

email (option): horror@blueyonder.co.uk

Mick Holmes has got a long nut on his 16H too. I think that's where I first saw it...but others get along fine with the short one. There is a variable here that I can't put my finger on...but I experienced no 'seat of the pants' lack of pick-up and acceleration when I dropped the fuel level...and it doesn't overflow when standing so I don't think it's a float needle problem.

Mine's not a rough one either so I don' think it would be shaking the carb harder than normal.

This is reminding me about an issue I had with my G3 carb. It has a tiny drilling in the bottom of the flange and even Martyn didn't realy know what it was for. But the nice people at Burlen sent me this wartime document, which explans that there should be no bleed hole on the side and the hole in the flange with acompnying collection slot on the inside of the flange is to allow excess fuel to drain.

When Martyn first rebuilt the carb, he used a standard jet block, but he's since filled the overflow bleed hole with a brass plug. Ron

email (option): ronpier@talk21.com