<<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
          <<  Lancair Builders' Mail List  >>
          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
>>

Just an update to my engine roughness issue -

I think I have figured out the problem.  What I was experiencing was highly
likely preignition.  This was confirmed after a conversation with Lycoming.
The skyrocketing CHT was the telltale.  Likely cause...  the Lycoming tech
rep asked what my timing was, and I responded 25 degrees.  He said "Oh,
that's your problem, it should be 20 degrees".  But, I say, my data plate
states 25 degrees of timing advance.  Turns out they had a service bulletin
out on that engine recommending changing timing to 20 degrees.  Appears they
had a problem with detonation...

I am surprised that they don't modify the data plate after a change like
that.

Matt
________________________

-- 3.  I am experiencing what is likely detonation after extending climbs.
-<<<SNIP>>>
-- about 23 to 24 degrees.  This is just speculation at this point, but
-- one time I was able to see that phenomena on the engine
<<<SNIP>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
LML website:   http://www.olsusa.com/Users/Mkaye/maillist.html
LML Builders' Bookstore:   http://www.buildersbooks.com/lancair

Please send your photos and drawings to marvkaye@olsusa.com.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>