Originally Posted by IBWET
JW: my engines are 24 Valve heads this has stopped me adjusting the tappets, one is noisey, it dosen't bother me,what chance do you think of dropping a valve etc?
A noisey tappet (within reason) will do no harm, is just softens the valve timing on that cylinder. You do not need to be anxious about setting a 24 valve engine. There are 12 normal rockers. To activate 24 valves, the rockers press on the centre of a lever which presses 2 valves at a time. The word lever here isn't a good description. The principle is simple. One end of the lever also has a screw and nut adjuster just like the rocker. This screw bears on the top of one of the pair of valves so that you can ensure both vales open at the same time by adjusting the screw. It is much simpler than it sounds. I also found that when one pair of valves was down, it was possible to adjust 4 rockers so making the job a bit quicker. The heal of the cam must be circular and the timing fairly conservative.
The method I used was to get 2 valves down and identify the rockers to be adjusted.
Slacken the rocker locknut.
Slacken the lever locknut and back off the screw a half turn.
Insert the feeler.
Tighten the rocker screw until the feeler is lightly gripped to remove all the slack. This also makes one end of the lever contact its valve.
Finger tighten the lever screw to bring it into contanct with its valve and nip up its locknut.
This has balanced the opening of the pair of valves so that they are the same. Now go back to the rocker screw and adjust the clearance in the usual way. Write down which rockers you have adjusted. Repeat for the other rockers. Rotate the engine until the next pair of valves are down and repeat the prodedure.
It does take a while to do the job but it's staightforward if a bit fiddly. It took me about 4hours in total and much of that was removing all the bits so that I could lift the rocker cover!
On my engine, the listed replacement rocker cover gasket was priced at about £130.
Needless to say, I didn't buy one.
It was a good job too because it wasn't needed. The rocker cover had the usual piece of rubber cord set into a groove machined into the cover and it was still soft and reusable.