bgsengine wrote:Yeah what KE4 said - but I'd say 6 or 7 thou ain't enough to worry about as far as measurements go (with less clearance, one could easily have valves too tight and bind in guides when engine gets hot! consider thermal expansion rates, I'd want minimum .003 clearance, which means maybe .003 wear, divide by 2 (since you're measuring 2 sides of wear when checking diameter) , and you have maybe .0015" of wear... ) - but as mentioned, the wiggle test comes from experience, and I can attest what KE4 says, you can only really know with more confidence after getting a new valve guide put in (or have a new engine block or short block to compare with) - Once you have done enough comparisons you get a real feel for it , but if I had to really think hard about it how .010" total wear might feel I think it would be getting close to where I might consider new guides, depending on what I expect of the engine in the future (Running hours, type of use, etc) - The plug gauge itself, obviously, allows for .020 total wear (.010 on a side) which to me is rather insane... Also, consider the length of the valve guide itself - a shorter guide will allow a lot more wiggle with less wear than a longer guide will.
I can say, that when I first started doing valve guides (since I had the tools, and it was MY shop so I didn't need boss approval) probably 85% of the ones I replaced didn't need it (In fact, on a couple early ones, the wiggle test got noticeably WORSE after I installed new guides.) Again I never paid that much attention to specs (I didn't have tools to measure bores that small!) but if you really do have just .007 of wear, I think your guides are fine. - Consider, as you said the plug gauge itself means Briggs has a wear limit of .020" on valve guides... so you're well within Briggs' specs, right?
OK- understood and GOOD NEWS! Perhaps I was a bit too conservative on my "wiggle test" conclusions? For now, I will hold off having a new exhaust valve guide installed. First, I'll get the engine running and see what the performance reveals (especially any evidence of oil burning/smoking).
Michael