Ed and Finn;  The engine that I have, I purchased from Atkins Aviation and I
don't know much else about it.  Looking in the Haynes Manual there is a
picture of some rectanglar metal pieces in the exhaust ports.  Are these
inserts used in the turbo engines, at any rate the engine I have doesn't
have those .  There appears to be some nearly round inserts in the aluminum
rotor housing, I assume these may be peculiar to all 13B engines.  Thankyou
for the info.  Next week i'll have to do some price checking with some
different vendors and go from there.  JohnD