Cam Belt – Sigma
Cam belt replacement on the Sigma engine should be carried out by a specialist like Premier Power.
The cam belt on the Sigma, like any other cam belt drive engine, links the crankshaft to the camshafts. These engines are mass produced, modified for Caterham. Being mass produced, this means the engines are assembled using specific tools that set the cam timing in relation to the crankshaft position for accurate positioning and set up. The positioning of the camshafts in relation to crankshaft positioning is crucial to performance and driveability of the engine as the engines ECU will have been calibrated to suit this set up.
The position of the camshafts and crankshaft on the Sigma are such that the drive sprockets, driven by the drive belt, are not located by a dowel or key. They are simply clamped by the retaining bolts. This means as soon as the bolts are loosened, the set up is lost. Whilst service tools are available to locate the cams and crankshaft in position, these are only suitable for the standard Ford camshafts which are not used in engines like the 140 Supersport and the 310R. On both the Fixed Cam Sigma and the Ti-VCT variant, the lower cam belt cover needs to be removed, to replace the cam belt. To remove the belt cover, the crankshaft damper pulley needs to be removed, this then means the crankshaft positioning is lost and hence cam timing set up is also lost. Premier Power measure the set up using specific measuring tools prior to removing the belt and then reset the cam timing to the original set up.
To replace the belt on a standard engine is a four hour job because of all the parts that need to be removed to get access to the belt.
Options whilst having the belt replaced;
Water pump and cam belt tensioner replacement.
Valve spring replacement.
Valve clearance measurement and adjustment as required.
Customers with Premier Power built Sigma engines;
If your engine has been upgraded by us and we have not fitted the belt cover, you will be looking at one hours labour to replace the cam belt. This is also due to F175, F190 and F200 engines having cam drive sprockets dowelled onto cams and crankshaft.
Price on application