BELT TENSION: The timing type drive belt, when all tightened down, should be "taught" 
not loose, but also not like a rubber band. There should be approximately 3,175 mm 
movement in up and down direction on the slack side of the belt. Some engine builders say the 
belt should be able to twist by hand, 90°. However, you choose to determine belt tension,
keep in mind that at no time should be belt be allowed to "jump teeth." This will result
in a worn out belt very quickly. While this drive method is virtually "bullet proof", 
a spare belt should always be carried with you.