Dripping pre monobloc

[G3L1946]

Hi

Thanks both. I’ll take another look at it today and see if I can locate the problem. I did lap the needle, gently by hand, using autosol.
If all else fails, I’ll put the old one back to see if that solves it.

Thanks,

Steve

[clive]

Autosol probably too gentle to lap in with. Fine grinding paste would be better. Its often worth thinking "why did this second hand part stop being used" and in this case become detached from the carb body? Possibly because it was allowing flooding. Should be possible to sort this though good luck.

[G3L1946]

Hi Clive,
Maybe I should have just left it alone in the first place! The carburettor fitted is a 76AE/1AK . The original would have been a 76D/1J. The specifications for the carburetors are the same ( the 76AE being used from 1951 on ) . It is the bowl angles which are different. 15 degrees for 76D but only 3 degrees for the 76AE. Fitting the replacement bowl gave me the required 15 degrees thus positioning the bowl in a more vertical orientation.
I’m not sure, but I have a feeling, that a later iron head may have been fitted during its long history. The exhaust outlet has a stub fitting for the pipe as a cooling type clamp has been fitted. I think this might be 1949? Would this have an implication re angles etc?

Thanks Clive,

Steve

1947 G3L motorcycle.

[clive]

My 49 certainly had stub fitting for the head to exhaust pipe and hairpin valves so a different rockerbox with valve lifter fitted. I had the later 76AE/1AK fitted with what must have been the 3 degree float bowl. Got it new from Russel's in about 1980! I would try the other float bowl and see if it still floods. Not a big job to change them over.

[G3L1946]

Hi Clive,
I’m not sure when the head with stub fitting first came out or when that style finished. The alloy head on my ‘55 certainly does not.
I’m going to remove tank and take off the 15 degree bowl and check it over. I’ll also test out the old bowl with the 3 degree. If my converted one leaks and the 3 degree doesn’t then ‘ if it ain’t broke don’t fix it’ !

Cheers,

Steve

[G3L1946]

Good morning,
An update. I replaced the bowl with the original and, although it is not vertically orientated, the drips have ceased! I have no idea why but, quite honestly, I don’t really care ( well, I do a bit due to my natural curiosity)!
I suppose it must have something to do with the fuel level within the bowl? Could it be that bowls are not as interchangeable as I thought? I did check that the float, needle and everything was fine as I dismantled the offending unit, so, the mystery remains but my drips do not!

Cheers,

Steve

[SPRIDDLER]

Maybe the grooves for the float needle clip for each of the chambers are at different levels?

[G3L1946]

Hi,
That would seem a possibility but there is only one groove. I’ve taken time to measure lengths, inside diameters of the bowl, depths etc etc. I cannot determine any difference at all between the two bowls ( except angle ) My only conclusion can be that the seating of the needle ( within the offending bowl ) is compromised somehow. Spares at Amal only show one type of float and needle for this series of pre monobloc.

Steve

[clive]

Good you are no longer dripping. " I don’t really care ( well, I do a bit due to my natural curiosity)! " I find it best just to ignore the big questions in life and ride the bike instead.

[G3L1946]

Your not wrong there Clive!

Steve