Fiat Uno Manual
Valve clearances - adjustment (1116 cc and 1301 cc engines)Engine / Valve clearances - adjustment (1116 cc and 1301 cc engines)
1 Check the valve clearances (Section 25).
2 Clearances which are incorrect will mean the particular shim will have to be changed.
To remove the shim, turn the crankshaft until the high point of the cam is pointing directly upward. The cam follower will now have to be depressed so that the shim can be extracted. Special tools (A60642 and A87001) are available from your Fiat dealer to do the job, otherwise you will have to make up a forked lever to locate on the rim of the cam follower. This must allow room for the shim to be prised out by means of the cut-outs provided in the cam follower rim (photo).
26.2 Removing a shim from a cam follower
3 Once the shim is extracted, establish its thickness and change it for a thicker or thinner one to bring the previously recorded clearance within specification. For example, if the measured valve clearance was 1.27 mm (0.05 in) too great, a shim thicker by this amount will be required. Conversely, if the clearance was 1.27 mm (0.05 in) too small, a shim thinner by this amount will be required.
4 Shims have their thickness (mm) engraved on them; although the engraved side should be fitted so as not to be visible, wear still occurs and often obliterates the number. In this case, measuring their thickness with a metric micrometer is the only method to establish their thickness (photo).
26.4 Shim engraved mark
5 In practice, if several shims have to be changed, they can often be interchanged, so avoiding the necessity of having to buy more new shims than is necessary.
6 If more than two or three valve clearances are found to be incorrect, it will be more convenient to remove the camshaft carrier for easier removal of the shims.
7 Where no clearance can be measured, even with the thinnest available shim in position, the valve will have to be removed and the end of its stem ground off squarely. This will reduce its overall length by the minimum amount to provide a clearance. This job should be entrusted to your dealer as it is important to keep the end of the valve stem square.
8 On completion, refit the camshaft cover and gasket.