28-06-2018, 02:04 AM
In the day many persons were experienced from work on bicycles, motorcycles etc and tended to use standard spanners of appropriate length so many got along perfectly without torque wrenches. Now persons lack experience and tend to use ratchet sets etc with one handle for all sizes and do not adjust the hold..
It is common to find be bolts stretched.
Some published figures for Sevens are plain wrong and others excessive; OK for the racers using exotic bolts.
The be bolts on Sevens are not heavily loaded; many much larger engines use the same size.High head tensions distort valve seats, bores, and prompt cracks.
Before using any figures it is prudent to compare with published figures for ordinary carbon steel HT bolts; it is unlikely the original materials were hugely superior. Important to distinguish the degree of lubrication or not intended.
It is a good idea to compare hand tension to calibrate yourself. You may not need a wrench.
It is common to find be bolts stretched.
Some published figures for Sevens are plain wrong and others excessive; OK for the racers using exotic bolts.
The be bolts on Sevens are not heavily loaded; many much larger engines use the same size.High head tensions distort valve seats, bores, and prompt cracks.
Before using any figures it is prudent to compare with published figures for ordinary carbon steel HT bolts; it is unlikely the original materials were hugely superior. Important to distinguish the degree of lubrication or not intended.
It is a good idea to compare hand tension to calibrate yourself. You may not need a wrench.