nrp wrote:
: The application of full power on an aircooled engine causes things to
: heat up very rapidly since there is little thermal inertia. On startup
: & taxi, the oil bypasses at the relief valve & doesn't get much access
: to the heat of the engine until you get to a certain point, where it
: really begins to remove heat, quits bypassing and then warms up
: quickly. The specific heat of oil isn't very high yet the heat input
: once things get to spraying around the crankcase are probably pretty
: substantial.

: Somewhere the intake manifold might be changing from a mixed
: liquid/vapor flow to an all vapor flow at a corner or an obstruction.
: Look up the manifold and on the carb gasket when you do the throttle
: plate bit. Check for loose clamps etc on the manifold tubes - but it
: sounds like your mechanic etc (I. e. you) are pretty well on top of
: things and have done that already.

I'll check that. Remember though, that it has done this in the summer as well
as now in the "winter." Not like the forecast high of 63 degrees today could really
be called "winter," but it was about 40 the last time it acted up. I'm pretty sure
when I left Milwaukee at New Year's time it acted up on takeoff too... probably 35
degree late-morning after a cold-soak overnight at 25 (with preheaters on).

: Q - How well did the Lycoming clearance measurement thing work? I
: built one but have not used it yet. Was your's per their plans?

Well, due to liability concerns, they've killed all the student-accessible
machine shops. I basically had to beg the shop to chuck up the aluminum stock into
the lathe and ream out the 0.496" hole. The rest of it I built with a spoon and my
teeth (i.e. drillpress and hacksaw). It was a crude approximation of the tool
outlined in the SB388, but it worked to extend the valve's stem. As far as
measurement part, I used a dial indicator with magnetic base and manipulated it to hit
the rod vertically at 2.5" from the valve guide as per the SB. I didn't build the
holder doodad that goes on the rocker arm pivot rod. Not very elegant, but
it did work... just more of a pain to set up and move from jug to jug.

The biggest problem that I had was how much to open the valve. When it was
well-seated (i.e. fully closed) the clearance was very small. One it was opened a
bit, it opened up to about the limits. The SB doesn't describe how much the valve
should be open. I suspect the magic Lycoming tool compresses the valve spring enough
to deseat the valve, but it never says how much.

-Cory


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************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
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