Adjusting the valve clearance to .010 inches on the W-670 with a feeler gauge bent at an angle, and with three separate lobes on the valve cam disc, can be tedious to say the least. A tool that makes the whole process a lot simpler and faster is shown on the right. This tool is made from a rockerbox cover that is cut off and contoured on both ends. A support tongue made out of ¼ inch aluminum is shaped to fit the underside of the cover and provide a mounting point for a dial indicator.
The dial indicator hole is directly over the center of the roller on the rocker arm. Two holes, 90 degrees apart, are drilled and tapped into the sides of the mounting tongue for thumbscrews to hold the dial indicator in position.
On the underside of the tool, mounted to the screw nearest the indicator, is a compression spring about 1 inch long and ¾ inch in diameter. (See Fig.5)
When the tool is mounted on the rocker-arm box with nuts drawn down snug (two are enough), the indicator hole is directly over the center of the rocker arm roller. The spring on the underside puts pressure on the forward part of the rocker arm holding the roller against the valve. The dial indicator is placed in the hole and positioned down until the indicator tip is about a 1/8 inch past where it first touches the roller, and the thumbscrews are tightened. Position the face of the indicator so that it is easy to see.
Now when the “ON” button on the indicator is pressed, it also zeros the indicator at that point.
Now when you press down on the back end of the rocker arm until it contacts the pushrod, the dial indicator will read the valve clearance accurately. However, a better way to do this is to put a small screwdriver blade under the roller and lift it until the back of the rocker arm touches the pushrod. This method cancels out any tolerance or slop between the roller and its mounting pin. (Fig.3)
By loosening the lock nut on the valve adjusting screw, you can turn the screw with the T-handle in the correct direction, retighten the locking nut, re-zero the dial indicator, raise the roller with the screwdriver, and get an immediate valve clearance reading from the dial indicator. (Fig.4)
Of course a better way might be to make the unit out of some properly bent up sheet metal instead of a rocker box cover, but this way you are sure to get the bolt hole pattern right. The dial indicator used on this tool is a Mitutoyo IDS-1012EB.