Valve adjustment, is .8 bad?


2 replies to this topic
  • Phillipps76

Posted January 06, 2007 - 09:59 PM

#1

I checked the valve lash and all were within the spec except 1 intake which was 0.8 (Supposed to be 1.0 - 1.5) I thought it would wear lose not tight? Is this bad and will it wear lose or continue to wear tighter?

Thanks,
Kelly

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  • Ulysses

Posted January 06, 2007 - 11:23 PM

#2

I checked the valve lash and all were within the spec except 1 intake which was 0.8 (Supposed to be 1.0 - 1.5) I thought it would wear lose not tight? Is this bad and will it wear lose or continue to wear tighter?

Thanks,
Kelly


If the valve seat is wearing then it'll get tighter. Whatever the trend, you need to correct it. You can't wait and hope for the best to happen. If it's getting too tight might not close completely.

  • grayracer513

Posted January 06, 2007 - 11:57 PM

#3

Well, let's see, minimum is .10...yep, .08 is bad alright.

The valves would only loosen if there was wear at the cam base circle (basically impossible), the lifter (possible, but quite rare), or the valve stem end (never seen it). All in all, it pretty much never happens that way.

What does wear is the valve face and/or the seat. This lets the valve move up into the head and closer to the cam.

You didn't specify your year/model, but if it's an '01 or later, it has Ti valves. Titanium valves are only hard enough to fill their role as valves because they are coated with compounds like titanium nitride. This coating is extremely hard, but is also very thin. Once these require their first adjustment, which can take well over 100 hours, they need to be watched more closely. If they hold the setting to which they were adjusted, then everything is still fine, but if they continue to close, the coating is worn through, and they need to be replaced as soon as practical. Don't run them after they have worn to the point where they have had shims smaller than .15 thinner than the original shim under any circumstance.





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