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amal carb fitted horizontally

methamon

Well Known and Active Website User
Non-VOC Member
Ho ho ho!

Does anyone know where there is quality information on amal type 6, 76 or 276 carburettors positioned with the mixing chamber horizontal and “special” float chamber to suit? I understand that several pre war bikes had carb’s fitted in this orientation including single cylinder machines. Can someone tell me which bikes they were?
I suspect that the front carb on my twin (horizontal fitment) is not operating correctly on tickover It strikes me that the carb will struggle to perform satisfactorily at low rpm i.e tickover but as these were fitted to singles they must have worked satisfactorily? It also strikes me that fuel level is absolutely critical; above main jet invert level (as it is horizontal) causes immediate flooding, a little lower impedes the ability of the carb to draw fuel. The carb body can be rotated about the inlet stub to lower the main but the extent is limited as this causes the float chamber to tilt of its axis with inevitable flooding consequences. This cannot be a new problem surely?
 

BlackLightning998

Well Known and Active Website User
VOC Member
Two thoughts...

Ho ho ho!

Does anyone know where there is quality information on amal type 6, 76 or 276 carburettors positioned with the mixing chamber horizontal and “special” float chamber to suit? I understand that several pre war bikes had carb’s fitted in this orientation including single cylinder machines. Can someone tell me which bikes they were?
I suspect that the front carb on my twin (horizontal fitment) is not operating correctly on tickover It strikes me that the carb will struggle to perform satisfactorily at low rpm i.e tickover but as these were fitted to singles they must have worked satisfactorily? It also strikes me that fuel level is absolutely critical; above main jet invert level (as it is horizontal) causes immediate flooding, a little lower impedes the ability of the carb to draw fuel. The carb body can be rotated about the inlet stub to lower the main but the extent is limited as this causes the float chamber to tilt of its axis with inevitable flooding consequences. This cannot be a new problem surely?

Hi,

There was a 1926 HRD at the Herts and Beds Rally last weekend like this - see the photo gallery for the picture but I'll post a thumbnail below.

Secondly, the bike belongs to Jacqueline Bickerstaff and I am sure she would know about it best, I don't have an email address for her but someone may be able to help you with contact details off list.

Regards

Stuart
 

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chankly bore

Well Known and Active Website User
Non-VOC Member
90 degree float chamber

I ran my Comet for three years in the 80's with a rear head and a horizontal type 289. I was told the float chamber was off a Douglas but that may be wrong. Anyway the bike went just the same!
 

methamon

Well Known and Active Website User
Non-VOC Member
Well thank you everyone for your contributions which were useful. Having pondered the problem for some time now I decided to repostion the entrance to the pilot jet at the base of the jet block. Following this the beast runs on both cylinder at idle and runs smoothly at larger throttle openings which it has never done since I bought it.
Whe I get a bit more time I will explain my reasoning and draw some diagrams illustrating the modification.
 
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