Fitting Amal Concentrics

I have Concentrics on my 650SS. To get around this problem I used Allan bolts instead of norm bolts and no longer a problem, no other modification required.  Good luck

Standard fitment with twin carbs was with three studs+nuts, plus a socket head screw on one of the centre fixings, for this reason.  The first one can be tightened with a spanner but the inner on the second needs the screw.

Hi- John, Billy and David, the 5/16 inch BSW cap-headed Allen bolt was also used on the standard fit monoblocs.   The right-hand chopped carb was secured by the two studs with hex-reduced nuts and reduced o/d washers whilst the left-hand standard monobloc used the Allen bolt for the centre fixing and the stud for the outer (with the reduced hex nut etc).  Good luck, Howard

Remove the studs and replace with Allan bolts as per attached picture

Sorry John didn't mean to sound like a dictator please accept as a suggestion only. It did work for me.

My 1965 Atlas had twin 930 Concentrics and was fitted with reduced nuts on the inner carb studs.
The removal procedure started with a small but longish open end spanner held horizontally on one nut. That spanner being turned using another spanner or bar on the free end. The first complete turn was painfully slow to manage but generally after this a finger would spin the nut fairly easily.
Replacing the small nut require a screwdriver shaft or thin rod for it to slide into position taking care not to cross-thread it.
Paul Goff used to sell quality lever fuel taps which gave a small reserve on a Dominator tank.

Extract from parts list shows 3 studs + 3 nuts + 3 washers, and one fixing screw (without a washer).

It's fairly common practice to file a bit off the blank bosses, to fit Concentrics parallel.

I use original Ewarts taps that I refurbish , These have a reserve position and last for years if set up right . Hard to find though .