Spreading the rails

On the mid sixties 250/441 BSAs there is 1/8" spacer on the bottom engine stud, on the drive side between the frame lug and the crank case. This is often overlooked during reassembly, resulting in the lower frame rails being tweaked in. 

Using a 7" length of M10 x 1.0 studding with two nuts on the inside of the rails the gap can be spread to the specified 4 5/8". 

Once the motor goes back in there will now be clearance which can be measured accurately and a bespoke spacer made to take up the gap minus 0.002" resulting in minimal movement of the frame when tightened.