350 NH float bowl

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Gui.dorey
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350 NH float bowl

Postby Gui.dorey » Thu Jan 21, 2021 5:51 pm

Need tour help again.

Been progressing with my 1954 NH and just overhauled the carburettor. As you know the inlet on the NH is at an angle and so the float bowl has a twist to compensate the slanted carb. This way it stays level.

However, I just noticed The float bowl which came with the bike does not have the twist so it is obviously slanted from level when assembled.

So my question is, will it even run like this, or it won’t even start due to a wrong fuel level and flooding? If that’s the case, it’s another part added to the urgently wanted list....

Cheers
Gui

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Re: 350 NH float bowl

Postby JohnnyBeckett » Thu Jan 21, 2021 6:39 pm

hi Gui, my NH 350 has got a amal concentric on it and the float bowl is underneath the bottom of the carb so it is on a angle and i have had NO problems with starting it or its running and riding it , so i think you will be ok using your carb :!: but someone may tell you something different but i can not see why :?:

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Re: 350 NH float bowl

Postby will_curry » Thu Jan 21, 2021 7:39 pm

I take it it's a 276 you have.
I think the angle is 15 degrees and it really needs to be right.

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simon.holyfield
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Re: 350 NH float bowl

Postby simon.holyfield » Thu Jan 21, 2021 8:38 pm

JohnnyBeckett wrote:hi Gui, my NH 350 has got a amal concentric on it and the float bowl is underneath the bottom of the carb so it is on a angle and i have had NO problems with starting it or its running and riding it , so i think you will be ok using your carb :!: but someone may tell you something different but i can not see why :?:


Think about the way the float moves. In a concentric or a monobloc it has a horizontal hinge, so the angle doesn't affect operation of the float. In a pre-monobloc, the float moves on a path where the needle is guided vertically. When the needle is at an angle, there's a lot more friction preventing it moving freely.
cheers

Simes

'51 Square Four,
'58 Huntmaster,
'42 W/NG,
'30 Model A
http://ariel-square-four.blogspot.com

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Re: 350 NH float bowl

Postby cmattina » Thu Jan 21, 2021 8:46 pm

JohnnyBeckett wrote:hi Gui, my NH 350 has got a amal concentric on it and the float bowl is underneath the bottom of the carb so it is on a angle and i have had NO problems with starting it or its running and riding it , so i think you will be ok using your carb :!: but someone may tell you something different but i can not see why :?:


Hey Johnny,

What are the specs (jets/filter) on the concentric you're running?
Charlie Mattina
1950(ish) NH350
Ontario, Canada

JohnnyBeckett
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Re: 350 NH float bowl

Postby JohnnyBeckett » Thu Jan 21, 2021 11:07 pm

hi Cmattina i think its a 626 MK1 but i can not remember the jets specs are, and i cannot go and look at the bike at the moment, because i have just had a big life changing operation and i will be off my feet for a few months i hope, :?: and i am running a bellmouth or a cone type air filter, the carb was got from surrey cycles a good few years ago and he jetted it and all i have done to it is adjust it to tickover nice, he is very good at surrey cycles i think he knows a lot about jetting and carbs, i have had a good few carbs over the years from them for different british motorcycles with not alot of problems getting them to run right i use concentric on most of my ariels and i think they run a lot better, but i know a lot of members will say its not the right carb for the bike but i think it is more reliable, :D :D than the old carbs , :?:

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simon.holyfield
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Re: 350 NH float bowl

Postby simon.holyfield » Fri Jan 22, 2021 9:15 am

I've got a new concentric for the FH - first time I have used one. The monobloc is certainly a much easier carb to live with than the older ones, so I am looking forward to learning about the concentric.

The Solex on the SQ4 is much better than the Amals I have though!
cheers

Simes

'51 Square Four,
'58 Huntmaster,
'42 W/NG,
'30 Model A
http://ariel-square-four.blogspot.com

cmattina
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Re: 350 NH float bowl

Postby cmattina » Fri Jan 22, 2021 6:27 pm

JohnnyBeckett wrote:hi Cmattina i think its a 626 MK1 but i can not remember the jets specs are, and i cannot go and look at the bike at the moment, because i have just had a big life changing operation and i will be off my feet for a few months i hope, :?: and i am running a bellmouth or a cone type air filter, the carb was got from surrey cycles a good few years ago and he jetted it and all i have done to it is adjust it to tickover nice, he is very good at surrey cycles i think he knows a lot about jetting and carbs, i have had a good few carbs over the years from them for different british motorcycles with not alot of problems getting them to run right i use concentric on most of my ariels and i think they run a lot better, but i know a lot of members will say its not the right carb for the bike but i think it is more reliable, :D :D than the old carbs , :?:


Thanks for the info! Wish you a speedy recovery
Charlie Mattina
1950(ish) NH350
Ontario, Canada

Gui.dorey
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Re: 350 NH float bowl

Postby Gui.dorey » Fri Jan 22, 2021 6:33 pm

So on further investigation it seems I have a completely wrong carb for my NH.

It’s a 276DK/1AT, which seems to be used for the Triumph 5T Speed Twin. It has a 15/16” bore instead of 1”. The needle jet is marked 107, but can’t make out what is on the pilot. The 1AT refers to the float chamber, which should be a 7 degree one, but not sure if it’s even the one I have. The only marking I found on the float chamber says
1DB/M - anybody knows what that means?
The slider is marked 6/ 3 1/2 which seems to be right for the carb. Also, does anyone know what the DK means?

Conclusion: I’m in the market for a correct carb for a 1954 NH...

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simon.holyfield
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Re: 350 NH float bowl

Postby simon.holyfield » Fri Jan 22, 2021 7:22 pm

A 1DB is a 7 degree bottom feed float chamber...

It's close to what you need I think. The Amal book says you should have a 276AZ/1J with a 120 main, 107 needle and a 15 degree float chamber.
cheers

Simes

'51 Square Four,
'58 Huntmaster,
'42 W/NG,
'30 Model A
http://ariel-square-four.blogspot.com


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