Just installed the new shims that were needed to open up the valve clearances. All of the old shims, and the new ones were checked and double checked with the same Mitutoyo (good, accurate, reliable brand, not a cheapie) digital caliper. All of my calculations were double checked and triple checked.

BUT . . . with the new shims installed the clearances were not as they should have been. Volvo specs for SETTING the valve clearance is 0.35mm to 0.4mm, or 0.014" to 0.016". Mine *should* have been in the range of 0.366mm to 0.397mm or well within the Volvo specs. Instead, I got 5 valves at approx 0.330mm, or 0.13", two at 0.356mm or about 0.014", and one at 0.38mm, or about 0.015".

The new shims should have increased the clearances by the differnce between their height and the height of the old shims. But, for example, a shim that measured 3.97mm was replaced by a shim that measured 3.85mm. The change should have been an increase of 0.12mm in clearance, but the acutal measured change was 0.076mm, which is much less than it should have been.

Thus, on five of my valves, the clearance is 0.02mm, or 0.001" too tight.

Is that enough to warrant changing the shims again to loosen up the clearance to be within spec?

And, should I worry more about the exhaust valves than the intake valves, because exhaust valves will be the ones more likely to burn from tight clearance?
--
Scott Cook - 1991 745T, 1985 RX-7 GSL-SE, 1986 Toyota Tercel (Don't laugh, it is reliable, faithful AND gets 41 mpg!)