Vernier Camshaft Pulleys

In order to optimise the timing of the camshafts, adjustable vernier pulleys are required. The standard inlet pulley on the Fiat 5-cylinder is already adjustable but the exhaust pulley is not. The standard exhaust pulley will move slightly when loose but not really enough to be useful. This meant a custom vernier exhaust pulley needed to be made and well, might as well make a matching inlet pulley whilst I'm at it!

The new pulleys are a nice, light, anodised aluminium. The inlet pulley is a single piece item, the same as standard but the exhaust pulley is actually a hybrid of the old and the new.  The reason for this is the cam phase sensor, required for sequential injection and injection. The sensor looks for a gap in a reluctor ring mounted behind the pulley. The exhaust pulley also has an odd keyway to locate it on to the camshaft which is hard to reproduce so instead of totally re-inventing the wheel, the teeth were machined off the old pulley, holes drilled and tapped in the spokes and a new outer pulley fabricated to sit over the top of it. This gives good adjustability whilst retaining the sensor pickup and keyway.