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Camshaft Fitting Instructions

Note: It is not recommend installing a performance camshaft in a vehicle fitted with an automatic gearbox.

The installation and first few moments of running are critical factors in the life of the camshaft. Failure to install the camshaft correctly will have a drastic effect on the life of the camshaft and in the worst cases can result in immediate failure. The following instructions must be adhered to in order to obtain maximum performance from the engine and to ensure a long and trouble free life from both camshaft and associated components.

These instructions are also provided in addition to the original manufacturers installation procedure.

Where a camshaft is being replaced due to excessive wear, it would be highly recommended to strip the engine and fully clean the internals. Metal particles present in the sump, oil pump, bearings and oil galleries will soon play havoc with the new cam. It would also be wise to check the oil feed system. Low oil pressure due to a worn pump, blocked pick-up pipe or blocked oil galleries will quickly wear the new cam to the same state as the one being replaced. In other words, before replacing a failed camshaft, make sure you find out the reasons for the failure and correct it!

Before fitting the camshaft, check that it is identical in every aspect (with the exception of the lobe profiles) to the one being replaced. Special attention should be given to the oil feed positions and journal diameters as variations may occur during the manufacture of the engine. Also check that any gallery bungs present on the old cam are also in place on the new cam. Do not remove the black phosphate coating from the new cam lobes.

Liberally coat both the camshaft and cam followers with a proprietary cam lube or engine assembly compound. Failure to do this can cause scuffing between the surfaces of the cam and followers, which will result in premature wear. Ensure that followers are free to rotate in their bores where applicable.

It is essential that new followers are always fitted, regardless of the condition or limited use of the old followers. Failure to do so may cause premature components failure and consequently will invalidate any warranty claim.

Upon installation, the valve springs must be checked to ensure that:

i) the fitted length (installed height) of the valve springs match the figure provided by the manufacturer (see figure 1). If too small, then the valve seat areas in the head will require machining. If too large, shims can be added to the spring seat. Due to varying manufacturing tolerances of cylinder heads, all springs should be checked and measured for clearance.

ii) coil binding does not exist at full valve lift. This is the condition where the spring is fully compressed (see fig 2). As a guide, the spring should be able to compress a further 0.060" (1.5mm) before the coil bound condition is reached. This can be checked by inserting feeler gauges between each coil of the spring and adding the results together to get a total clearance figure. Due to varying manufacturing tolerances of cylinder heads, all springs should be checked and measured for clearance.





Figure 1



Figure 2


Check the clearance between the bottom face of each retainer and the top of the guide or stem seal at full lift (see fig 2). This should be a minimum of 0.080" (2mm). If this clearance cannot be achieved, the top of the guides must be machined.

When double valve springs are being installed in place of singles, ensure that the inner spring is correctly located and the correct retainers and platforms are used where applicable.

When modifying engines that utilise finger followers i.e. SOHC Pinto, it is imperative that you ensure the followers remain in the original attitude relative to the cylinder head. Failure to do so will alter the rocker geometry, increasing or decreasing valve lift and can result in failure of both cam and followers or excessive valve stem/guide wear. For OHV engines, attention should be paid to rocker arm geometry for the same reasons.



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Last updated 1/1/17
© 2015

E-mail: Mark@Swetnam.co.uk


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