Some things that man puts together are never meant to be taken apart. I currently am working on an Austin Healey BJ8 which has the HD8 type SU carburetors. These carbs are attached with four 5/16 24 nuts each and due to the design of the BJ8 they are nearly impossible to get off. The float bowls are positioned between the two carbs and it is very difficult to get a ½” wrench in between to remove the lower/inner nuts. There are many other situations on our cars, such as brake master cylinders on chrome bumper MGBs. The retaining bolts are accessed from under the dash through a blind hole.
It would be easier to remove these if you could use a smaller wrench which would give you more access room. The simple answer is to use a jetnut. These nuts come in the standard sizes we use from Pegasus Auto Racing. The nut will fit the standard fastener but has a smaller hex head thus allowing you to use a smaller wrench or socket.
This is what they look like –
