| For
years I have had inter cylinder baffles on my Lycoming 0-320 that I made
myself. These are the baffles on the bottom and top sides of the engine
between the cylinders. I fashioned them after some I had seen on some other
0-320 that I had seen I suppose. It’s really been so long ago that I don’t
really remember. My engine seemed to run pretty decent cylinder head temps,
so I was never concerned about those baffles.
While I had my engine down
to find the cause of a bad oil blow-by problem, my engine shop man and
I got to talking about the baffling I was using. He showed me the factory
inter cylinder lower baffle that Lycoming makes for down draft cooling.
All he had was one for an 0-360 which is ½" longer than for an 0-320.
There was a lot of difference in the ones I have been using and those.
I figured Lycoming must know more than I do, so I used |
his
0-360 version as an example and made a set (2) just the same (but shorter)
for my 0-320 engine. It wasn’t easy because they are pretty involved as
far as sheet metal work goes.
I am now flying the plane
and they are working well. Since I made a number of improvements in my
baffling and other areas to help the oil cooling, I can’t say for sure
how much of the improvement is due to the Lycoming inter cylinder baffles
if in fact any. I can tell you that they sure didn’t hurt anything. I can
also tell you that they are available from your used engine place, aircraft
fly markets, or new (expensive) from Lycoming. I suggest you look for them
at the used parts dealers, but if you can’t find them anywhere else, I
am a Lycoming dealer and I can get them for you. It will cost you, but
at least it will be one part that you won’t have to make. |
| On
Lycoming engines, there is a 3/8" aluminum tube that goes from the side
of the head just below the rocker arm cover down to the crankcase. It is
connected to the crankcase with a short piece of 3/8" rubber hose and hose
clamps. This tube returns the oil that lubricates the rocker arms back
to the crankcase. Normally, these tubes are routed underneath the cylinders
in a fairly direct route to the crankcase. Since the normal Glass Goose
exhaust system manifold is routed right under the cylinders between the
bottom side of the cylinders and the intake tubes, there is a conflict
with these drain back lines.
The drain back lines are
subject to a lot of heat off the exhaust manifold if they are routed through
that area. I have always had concern for my oil temps and have been searching
for better ways to deal with oil cooling or avoiding unnecessary heating.
In the real heat of summer here in Texas, I could easily get up to the
limits. The cylinder head temps weren’t a problem. Just the oil temps.
While I had my engine out
this time, I really gave |
a
lot of thought to this and found ways to route the drain back lines completely
away from the exhaust manifolds! I actually found that one of my drain
back lines was running parallel to one of the exhaust manifolds about ½"
away from it! Since the manifolds run red hot under power, there had to
be a lot of heat going into the oil draining back in that line? Now I actually
have 3 of the 4 lines running around in the front of the engine exposed
to the fresh cool air! It may not be much, but it must contribute to oil
cooling somewhat and at least there is no heat going INTO them. The 4th
line crosses at 90° about 2" above the right exhaust manifold in the
back of the engine. I covered that line with 3/8" fire sleeve to insulate
it from the heat. Some small sections of the other 3 lines are within the
baffling where the air is at least somewhat hot normally and I also covered
those small sections with fire sleeve. Where the lines were exposed to
fresh cool air, I did not cover them.
One of the challenges in
routing the lines is that the lines must run downhill all the way from
the cylinder to the crankcase. This is a challenge believe me. I |
