someone out my way dropped a valve seat on a U20 recently and then spent
about 15 minutes trying to get it to rev up and smooth out. highly not
recommended, the valve kept making contact with the piston and would bend
just a tad each hit, scooping out little metal shavings. these welded
themselves to the top and sides of the crown of the piston, scoring the
cylinder wall badly. engine probably only had 20k miles on a rebuild. he's
putting a SR20DET in there now, not cheap to rebuild the U20's and wouldn't
have been necessary had he just shut it down and looked around for what was
wrong. gradual changes in how they run suggest tuneup stuff, sudden radical
changes are a good reason to shut down and look around.
just my 2 cents...
Craig
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