AC Engine Project
Life for The Weller 2 Litre 6 Cylinder Engine
Adjustable Camshaft Duplex Chain Sprockets are now in stock
Used in conjunction with the Camshaft Timing Procedure described in the FAQ's, this will assist in setting the cam timing to the exact requirements to suit the camshaft . This is an essential procedure to obtain optimum performance is possible whichever engine tune you have.

It should be noted that most camshaft sprockets will be worn as no spares have traditionally been available; sometimes it is thought that only the chain wears & replace only the chain without consideration for the sprocket.


The Duplex Sprocket is made from 0.45 carbon steel with the teeth induction hardened to 45-50 degrees Rockwell C'.

The Duplex sprocket is designed to ensure the chain beds into the teeth & is not held up by the shoulders as on the original design.

Angular movement of 15 degrees is available and the sprocket may be rotated by a further 18 degrees if needed by means of a second series of tapped holes in the boss.

To ensure the sprocket is uniformly held on the camshaft sprocket boss, six special locking shoulders hi tensile screws are used evenly spaced around the sprocket.

Once the chain is assembled on the sprocket & joined there should be no reason to split the chain again when setting up the timing, this is particularly true when using the setting procedure described in FAQ's.

If this setting procedure is followed, no further adjustment is needed, limiting the potential movement to a maximum of 15 degrees is also a safety feature in the unlikely event of the sprocket moving, if greater movement is allowed then valve & piston damage could occur!

After following the setting procedure it is good policy to re-check the timing after rotating the crankshaft as there could be some discrepancy as the Wellar tensioner settles to its normal position, the adjustment provided should be adequate to correct any change in settings.