11-04-2018, 08:03 AM
Hi Mike,
The concept of "Tightening torque" is a post WW2 idea. Before the war, mechanics were supposed to "know" the feel of a bolt and how to tighten it, hence no advice was given by the manufacturer.
That said, even if the 1/4" BSF bolts are R grade, the maximum torque is low, around 9 ft-lbs, which you may need a smaller than average torque wrench to measure.
http://www.jag-lovers.org/xk-lovers/library/torque.htm
You can google torque values for R grade BSF and Whitworth bolts as above, beware though, some modern fastenings (head and manifold studs) have been made from some poor quality steel in the past and cannot withstand much torque
Good luck!
The concept of "Tightening torque" is a post WW2 idea. Before the war, mechanics were supposed to "know" the feel of a bolt and how to tighten it, hence no advice was given by the manufacturer.
That said, even if the 1/4" BSF bolts are R grade, the maximum torque is low, around 9 ft-lbs, which you may need a smaller than average torque wrench to measure.
http://www.jag-lovers.org/xk-lovers/library/torque.htm
You can google torque values for R grade BSF and Whitworth bolts as above, beware though, some modern fastenings (head and manifold studs) have been made from some poor quality steel in the past and cannot withstand much torque
Good luck!