|Valve cover is off and I'm ready to start measuring clearances and removing shims. It takes about 30 minutes to get to this point.|
The shims I ordered from Pelican Parts on Sunday arrived via USPS on Friday. Perfect timing. So this morning I finished the job. Unfortunately, when I put the new shims in place, most of the clearances turned out tighter than I had calculated them to be with my spreadsheet. A couple were just under the minimum and I wasn't comfortable with that. Upon re-measuring things today, everything was measuring bigger. Checking my technique with the micrometer with the new shims of known thickness, I think I was cranking down too hard on the micrometer last week. You can definitely influence the measurement by how hard you turn down the dial. Once I standardized my technique and got consistent results, I ended up re-measuring all the clearances and moved several shims around to get closer to the clearances I wanted. My main concern was to not leave any valves too tight as that can lead to problems. In the end, I got all the clearances on the lower end of the tolerances. The minimums are 0.18mm on the intake cam, and 0.28 on the exhaust cam, while the maximums are 0.23mm and 0.33mm for the intake and exhaust, respectively.
Most interestingly, and to my surprise, the engine really does feel smoother and a little bit quieter after the adjustment. I swear I can feel and hear the difference. I didn't expect to. The S54 really likes proper maintenance. I also took this job as an opportunity to inspect the bolts on the VANOS system as there have been internet reports of them backing out and causing catastrophic failure of the timing gears and chain. Everything looked absolutely perfect so I didn't touch a thing there. I feel better having had a look at them, though.