Rhys,

Paul knows a lot more about the ramp design than I do, but the fact that noise reduces dramatically with tighter lash must mean that impact forces are reduced, no?

If you're setting for .018" cold, that will be very close to .016" hot. Check it sometime and see if the clearance doesn't tighten up that much with the engine fully heat-soaked. I use .016" hot as the stock setting for engines I don't own, and have not seen any degradation in idle quality with any Volvo cam at that point, although some retuning may be necessary if the engine was last tuned with the valves set loose.

I do find that the lash is more consistent when set hot -- why I don't know. Setting cold is fine for a start, but that lone ticky valve always quiets down when redone hot. It doesn't take more than ten minutes to do an accurate adjustment, so uneven cooling is negligible. Note that the DOHC XK motors that require cam removal for shimming don't have the extremely long valve trains found in our OHV motors -- they don't care about temperature; they're not going to change like ours do.

This has been the case with any number of B18D, B18B, B20B, B20E and B20F motors I've fiddled with. Performance improved in every case; it's not an anomaly that's being accidentally corrected.

The iPd/Isky cams hate anything under .018" hot. The C cam loses a bit of bottom end at around .014: hot, but still idles perfectly if the engine is retuned to suit. I agree that this is a poor man's way of increasing duration and high end power, so it's just something I was experimenting with on one of my own engines and I liked the results. I know budget-minded racers who are running D cams way tighter than that with no problems.

The Green Book method and the Haynes method are fine on paper. In real life, uneven spring loading of the rocker shaft and cam results in the outboard valves ending up at least .001" looser than the center valves. The method I prefer requires turning the motor eight separate times for a total of two full crank revolutions -- it's a bit more work, but the valves all come out the same.

I have never had any problem whatsoever with valves, seats, cams or lifters in any motor I've run at these clearances. Not once on any of my motors or the many motors I've worked on for friends. This forum is replete with tales of earplugs needed on the highway, wiped out cams, lifters apparently made of butter, cracked valves and at least some amount of pinging being normal. Coincidence?