While the main (front) cambelt is quite easy to time in the normal manner, the timing position on the rear cambelt and gears has the inlet camshaft at a position where the valve spring action is trying to turn the camshaft. This is a real nuisance as you end up fighting it as you manoeuvre the gears into place. Here’s what I do:
- On the bench, mesh the two gears with the belt in the timed position (marks lined up). (Note that the two gears are identical, and each has 2 timing marks – one for use on the exhaust the other if the gear is on the inlet. One gear has the concave facing you and the other the convex, and the marks to use are the ones on the face upwards side in each case rather than the marks on the face sitting on the bench.)
- Paint a couple of dabs of white marker on the belt and each gear, in a position where you can see them from above once they are on the engine! These white marks give you an easy visual reference that the gears and belt are still in time.
- Get the camshafts to the timed position.
- You’ll now notice what I said above about fighting the valve spring to keep the rear inlet camshaft in place. Don’t fight it! Let it rotate a few degrees so the spring is no longer acting. The camshaft will now be turning easily free of any spring influence.
- Turn the exhaust camshaft the same direction and the same amount. This is perfectly safe to do as the pistons are only halfway up the bore and all inlet valves are closed.
- Keeping the gears in timed mesh with the belt, turn them the same amount too.
- Still keeping the gears meshed with the belt, fit the inlet gear to the camshaft.
- Because the inlet camshaft is in a position where it can turn freely either way, rotate the inlet gear (still engaged with the camshaft and belt of course) whichever way is needed to get the exhaust gear and camshaft dowel to line up.
- Push the exhaust gear onto its spigot.
- Check from the aforementioned white blobs that everything is still timed.
- Do up the bolts holding the gears. ALWAYS use a good grade of Loctite on the camgear bolts unless you fancy joining the ranks of those who have had gear come off and valves tangle.
- Rotate the exhaust camshaft until the gears at the front of the engine are in the timed position, insert the locking tool, and fit the front belt.
I may have itemised it into a lot of steps, but it is in fact a quick and simple operation.