Bolting on to a pulley

If your pulley has existing mounting holes on it, as many do, then providing that you have a way of centering the wheel then it makes sense to use them to fasten your trigger wheel. I prefer to use countersunk allen headed bolts but any bolt that fits will do, just make sure to use thread-lock on the threads.

If your pulley doesn't already have bolt holes then you can drill and tap suitable holes into your pulley. 4-6 holes of M5-M6 size are required, more on a larger pulley, less on a smaller one. I prefer to center everything and clamp in place, then drill all the holes in one go, then countersink the trigger wheel separately for the bolts. If the pulley is cast iron then extra care should be taken during the tapping process. During final fitting make sure to add thread-lock to the bolts.

The Ford CVH pulley is a pulley with lots of options. Some pulleys were fitted with 36-1 teeth from the factory but if you don't have one of those pulleys and can't easily get hold of one then it is very easy to fit a ring gear trigger wheel. This particular pulley features a recess which is just the right size to locate the ring-gear. With the wheel located then it would an ideal choice for welding providing that it doesn't have a rubber damper insert. The CVH pulley has plenty of meat into which you can drill and tap for 4-6 4mm bolts, which is the method that we demonstrate here.

Ford CVH pulley	Ring gear wheel drops nicely on the pulleys built-in recess
The wheel has been clamped in position, marked up and four 3.2mm holes drilled through the wheel until they mark the pulley below	Wheel removed and the pulley itself is now drilled, again using a 3.2mm drill although a 3mm drill and a bit of wiggling would also work
A 4mm tap is now used to make a thread in the pulley holes	The finished wheel. It is essential to now verify that the wheel is properly centred. If necessary file the holes to give you some adjustment space
The finished wheel. It is essential to now verify that the wheel is properly centred. If necessary file the holes to give you some adjustment space