I bent a 7mm open ended spanner in a shallow S shape and could get this on the nuts by sliding it in below the cylindrical manifold water channel. Bolts will be held by the cable which goes through the drillings. Easing the bolts towards you with a thin screwdriver helps access to the nuts. I assume nuts are on - I wouldn't like to have to screw these on unless I had the carbs off.
To Dave 44.
Thanks. I'm making up a 7mm spanner and will crank it as you have done. Thought there might be special tool around for this.
Also I thought about taking nuts off and reversing the fitting so the nut was on the 'outside' .
You have/had 105?
Did consider reversing the bolt but decided this would misalign the cable which is held by the pinch bolt at the top of no.2 carb.
I've a 1967 Duetto with a period 1750 engine and a Mito. The 105's are addictive. They go so well when right and the engineering quality is fantastic - as good or better than Mercedes I've had. I enjoy maintaining mine and after having an early Sprint GT and a Spider Junior probably know every nut and bolt, at least on the pre-hydraulic clutch and injection models.