valve shim selection

[backyardbill]

If you were going to buy all new valve shims because none of the existing one's will put the valve gap in spec in a newly refurbished head (cleaned, new gaskets and seals, valves lapped in), would you shoot for gaps in the middle of the range, high end, or low end? Or doesn't it matter? I'm thinking that as the valve face and seats wear, the valve lash gets smaller and eventually will burn the valves.

Such as to be in the middle:
intake 0.015 - 0.019, so select a shim the will yield a gap of 0.017
exhaust 0.018 - 0.021, so select a shim that will yield a gap of 0.0195

These numbers came from the shop manual section 101.07, page 10-70, which BTW the millimeter values don't seen to calculate right: 0.015" is .381 mills

Any thoughts?

Thanks

[bradartigue]

It doesn't matter unless you plan to use it as a daily driver and put the engine through many cycles. I say this because I know like any enthusiast you're going to check it annually and make adjustments as necessary. If anything I shoot for the most even gap among all valves in a bank (I/E). Makes things smoother or so I've been told.

[backyardbill]

Thanks. That's how I measured it out, to make it in the middle of the range and even across.

[engineerted]

Bill, are you using performance cams or stock? You can go the extreme and measure actual duration for each lobe and shim accordingly.

[majicwrench]

When I check valve clearance on an engine that uses shims, clearance can and ususally is all over the place. Some will be tight, some will be loose. If I had to say, I would say that more are tight then loose.

The last toyota I checked clearance on had several very loose. Really high mileage.
Keith

[backyardbill]

engineerted: they are stock cams.