Checking the valve clearances are set correctly enables better starting, performance and engine life. Adjusting the valve clearance needs to be carried out correctly. It makes more sense to carry out this operation when changing the engine oil as the rocker covers need to be removed to access the valve rockers. The engine needs to be cold to check or adjust the valve clearances.


Raise the bonnet, remove the valance panels on top of the front wings and remove both front wings after disconnecting the wiring to the indicators. The rocker covers are at each end of the cylinder heads and held in place with a single nut. Place a suitable tray under the rocker cover to catch any oil that comes out when you undo and remove the rocker covers (they may need a sharp tap with a block of wood to break the seal). Clean the faces of the covers and cylinder heads ready to refit covers.


Inlet and Exhaust (engine cold): 0.006 to 0.008 inches - with the introduction of unleaded petrol some experts suggest as much as 0.012 inches.
Using a suitable socket, turn the engine over via the cooling fan fixing bolt until a valve spring is fully compressed (valve is fully open) now check the clearance on the corresponding valve on the opposite cylinder. Holding the rocker arm into the push rod seat, check the gap using the correct feeler gauge. The feeler gauge should be a firm sliding fit between the rocker arm and valve stem. Carry this out for each of the valves.

If the clearances are wrong they can be adjsuted as follows. Slacken the adjuster lock nut using a ring spanner, adjust the adjuster with a screwdriver until, using the correct feeler gauge, you have the correct gap. Holding the adjuster with the screwdriver tighten the lock nut and then re-check the gap. Once all the valves have been checked and/or adjusted turn the engine a complete turn and re-check clearances.


Apply a thin layer of gasket sealer (we recommend blue Hylomar or Loctite 598) to one side of the rocker gasket and to the sealing edge of the rocker cover and wait for the sealer to go ‘tacky’. Once ‘tacky’ fit clean side of gasket into rocker cover and fit cover to the cylinder head and tighten down with nut. Do not over-tighten as the rocker cover will splay out at the sealing edge and become distorted. The rocker cover only needs to be tightened a little more than hand tight.

Refit panels in reverse to removal, reconnect indicator wiring and don’t forget to refill or top up oil level.
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