*** IN STOCK SHIPS TODAY *** Jack blocks are used to mechanically tighten the belt rather than using a pry bar, by hand or piece of wood to get proper belt tension. There are 3 different lengths of jack blocks offered. We do this to suit the many combinations of belt lengths, idler pulley diameter, belt type, overdrive, etc.
Many choose to buy all three lengths or simply install the idler assembly, take a measurement, and then order the correct length blocks. Front jack block is .640" thick, rear jack block is .860" thick and jack bolts are 3/8"-24 thread with a 9/16" hex head.
The way these work is you leave the large idler nut just loose enough to slide and then tighten the belt with the two 3/8" stainless bolts a little at a time on each side to ensure the belt is square and straight. Tighten this way until you are happy with the belt tension and then tighten the large idler nut.
Now here is where guys do different things. Some remove the jack blocks and some leave them loaded and tighten the lock nuts. Both ways are acceptable.
Racer can chose jack block kit from drop down menu. Each kit contains one front block, one rear block, two jack bolts and jam nuts. Jack screw blocks measured end to end are as follows Short 2.630", Medium 4.250" and Long 6.00"