It may be necessary from time to time t adjust the tappets, and up to and including engine no. 223 this should be done in the following manner when the engine is thoroughly warm. The flywheel should be turned till the line that is marked both 1 and 4 is on the top. No. 1 cylinder should be on the firing stroke, and the tappet then set to .015". The engine should then be turned till the mark 2 and 3 are on top, and the process repeated. After engine no. 223 the same procedure should be used but the inlet tappets are set to .004" and the exhaust .006" both set when the engine is hot.

Short chassis Speed Models and any cars that have been modified to the 1926 Speed Model specification should have their tappets set at .019".

Very occasionally a valve spring breaks and when this occurs it can be changed in the following manner. The cover over the valve should be removed and also the bridge piece that holds the rockers in position. The rocker arm rob is then removed complete with the rockers. It is as well to note here that great care must be exercised when replacing the bridge piece, to tighten it down evenly otherwise it may fracture.

The cylinder whose spring is going to be changed must now have the sparking plug removed opposite the valve concerned. This is so that a rod can be inserted in the plug hole to maintain an upward push on the head of the valve and so keep it in place. The valve spring collar should now be pushed down, and the two taper cotters removed. The retaining collar can now be removed and the spring changed. Ensure that the tappets have clearance when the rockers are reassembled.