RL>Hello Lance!
RL>On 22 Apr 95, Lance Maresh hammered on the keyboard to James Dixon:
RL> LM> The only time you run into problems with an ABC engine and nitro
RL> LM> is when you break it in on low % and then later try to run it on
RL> LM> hi%. If you break it in on 30% and then later want to run 20 or
RL> LM> 15% you shouldn't have any problems, as a matter of fact if the
RL> LM> engine is getting tired and has been running 30% you may find a
RL> LM> bit more life in it by going to a lower % nitro fuel.
RL>It's the other way around.  As you increase the nitro content, the
RL>cylinder temperature rises, causing more expansion of the piston,
RL>which generally expands more than the sleeve and case.
RL>You can 'breath new life' into a tired ABC by going from 10% to 15%,
RL>but not the other way around.
Sorry Rich,
Since I'm for sure no engine expert I was using the words of one when I 
posted the reply to James. The expert I'm referring to is Clarence Lee.
In the November 1989 issue of RC Modeler on page 188 Mr. Lee states, 
"For this reason, an ABC type engine should always be broken in with the 
same fuel that is intended for flying after break-in, i.e.,you would not 
want to use low nitro fuel for the break-in and then go to high nitro 
for flying or racing. Operating temperature and clearances would be 
different. An engine broken in with 15% nitro fuel would be too loose 
for 40% nitro or higher. On the other hand, an engine run on 40% or 
higher fuel that is getting slightly over the hill, as far as 
piston/sleeve fit, would be just right for 15% fuel."
So as they say, "just the facts", and here's my source, by the way this 
is probably the first time I've been able to back up something this 
well, I usually go running off with my tail between my legs(G).
Regards,
Lance
--- GEcho 1.11+
 * CMPQwk #1.4 * UNREGISTERED EVALUATION COPY
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