I have a Concentric Mk1 on my B40 star, which I have taken off & dismantled to investigate if this could be the cause of the rough idle. ( the carb is set up as spec for the 1967 B40 Australian army B40, the only difference being it had a paper air filter & I have the gauze filter)
I've probed & carb cleanered/blown out the pilot jet airways, which seemed clean and not obviously the problem.
Having read Busman's advice and Amals, which seem to conflict, I'm not sure how to measure the float height. So advice appreciated.
Bushman's:
has a annotated photo saying "Push down here between pin and needle with flat blade screwdriver" & "Measure 80 thou (2mm) here"
I get where to measure 2mm, but should I be pushing down on the tangs of the float ? If I do this my float is about 1mm below the level with the bowl top...so 1mm too high ( when I don't push too hard as it goes all over the place if I do that)
(I've seen videos on youtube where the needle is pushed down. If I do this the float is 4mm below the bowl top edge)
HOWEVER Amal's advice on height seems different
Amal from their website:http://amalcarb.co.uk/rebuilding-mark-1-concentric-carburetter
The correct fuel level for all Mark 1 Concentric carburetters is 0.21" plus or minus 0.040" below the top edge of the float bowl. Thus when the needle valve is being held shut by the tangs of the float, the level of the fuel will be between 0.17" to 0.25" (4.33mm to 6.35mm) from the top of the bowl.
using Amal's advice it looks like I should be pushing down on the tangs of the float to measure...& my float is far too high ?
Advice welcome on what I should be doing.