Posted for "Chatfield S. Daniel" <csdaniel@FNBSouth.com>:

 It is really a liability thing.  You can make a certified engine
 experimental and vise versa.  Also you can have a certified engine in an
 experimental airplane but not an experimental engine in a certified
 plane.
 When I bought the engine for my RV-8, the engine builder asked if I
 wanted an experimental or certified engine.  I asked what the difference
 was and he said the only difference is one has a label and one doesn't
 and the certified engine cost an additional 3-4 thousand dollars due to
 the associated liability.  I have an experimental engine the RV and a
 certified engine in the ES.  It sounds like your engine builder is
 trying to dodge his responsibility.
 
 Chat Daniel
 

"""
 Experimental engine.
 I am not sure, but I think I read something many years ago about engines
 being in an experimental and removed are not certified to go back into a
 certified airplane. I think it went on to say, if it was torn down and
 inspected it could be be returned to service. ???
 Gene Underland
"""