How To: Tappet Adjustment - Speed Six Engine

Always read these instructions thoroughly and completely before starting work. This will prevent the inevitable happening, when half way through you realise you haven't got the neccessary tool or part required to complete the job.

1. Remove the top cover, all sparkplugs and camshaft cover.

2. Push rags into the plug holes just so nothing can be dropped into the bore. The rear of the head has a large oil way on the exhaust side at the end of the cam by the bulk head, you have to put a rag in there also just in case a shim drops (if one does the engine will have to be stripped so be careful).

3. Measure the gaps:

  • Inlet is 5-7thou gap
  • Outlet is 10-12thou gap,

To measure them, turn the engine by a rachet or spanner until the cam lobe, at its top of its lift, is pointing up at you. The valve should be fully closed. Measure each gap on all.

It is best that you make a table on paper with each valve having three boxes so you can write down the results eg inlet v1

cell 1 - 6thou

cell 2 - size for shim

cell 3 - size of shim needed

4. If the back ones are more than 2thou more than max, do them, if not leave alone.

5. If the gap of the valve is too small eg 3thou then the shim needs to be smaller than the original shim. To get the shim out you have to use a small bar or bent screwdriver; compress the valve spring, get a magnet to get the shim from the collet and repeat this on each one that is out. If the gap is too big eg 8thou then the shim needs to be bigger than the original shim.

eg. shim size 294thou would require a shim 296thou to close the gap to 6thou .

Just be careful do not drop any thing. If you do make sure you get it back you cant just take off the sump it is a full strip down to remove it as all the timing chains have to come off.