REFLECTOR: N4PE Testing Status

[Brian Michalk]

As I mentioned in my earlier email, my last flight was cut short due to 
high oil temps.

I've had five flights so far, and after each flight have been addressing 
the squawks.  The biggest danger to flight so far was a manifold 
pressure tube that got hot in flight, and appears to have collapsed 
after landing with low manifold pressure.  I replaced it with a larger 
tube good for 250F in the engine bay.  That should keep the EFI computer 
happy.

On my flights I have been having high CHT's, and of course the high oil 
temps that follow.  I have made several changes, but next on my list is 
to richen up the mixture a bit more from what I have now, which is just 
rich of best power.  I'm using electronic fuel injection.  I am also 
going to try the following:

  * Seal up all of the gaps around the plenum.
    When I tuned the engine, I used leaf blowers connected to the
    plenum.  This was more than adequate for engine cooling, and also
    kept my oil temps down, so I do believe my CHT temps are the root of
    the problem.  With the blowers, there were obvious leaks around the
    plenum.
  * Clean up the sharp corners from the armpit scoops to the engine
    I'm not giving up on the armpit scoops yet, and really don't want
    to.  I have my reasons.
  * Reduce the timing.
    I've got everything at 28BTDC until I get to 2600RPM, which advances
    to 32BTDC.  That should give me a little bit more headroom.
  * Richen the mixture
  * Cylinder baffles
    I can try this, but I'm not sure how it would really work.  The
    Franklin cylinder castings are such that there is really not much
    room for air to flow between cylinders.  On a Lycoming, the cooling
    fins go all around, but on a Franklin, the castings are much
    different.  It's difficult to explain, and really requires a
    picture.  Has anyone added the under-the-cylinder baffles to a Franklin?

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