Cessna 150 Cruising

I had a combined CHT/EGT installed recently.
A poster (MichaelR) suggested to go full throttle.
My advice: Don't do that.
Your CHT will be to high, you'll set yourself
up for frequent cylinder overhauls.

I take off full throttle and then throttle back
to 2600. The CHT will be around 380 F, below
the 400 F mark my mechanic advised me not to
exceed.

With 2600 RPM, I get about 95 knots indicated.
(My C150 has no wheelpants. Word is, you'll see
5 to 10 knots more with wheelpants.)

Typical cruising altitudes for me are 3500, 4500
and 5500. Went to 10500 once, overflying SFO
class Bravo (full throttle of course), but the CHT
was slightly over 400 F and this is not the best
thing to do. I don't think I'll do that again.

Ron,

I had my C-150 re-baffled a year ago. In the summer, the oil temp gauge
climbs pretty high but it doesn't go all the way up. I do have an
autofuel STC and it does seem to run a bit cooler on 100LL. My first
question is, how does one check to see if the gauge is calibrated
correctly? Also, might the retarded timing for the C-150 cylinder issue
contribute?

Thanks,

Pat


Ron Natalie wrote:

"Anony Mouse" wrote in message om...
I had a combined CHT/EGT installed recently.
A poster (MichaelR) suggested to go full throttle.
My advice: Don't do that.
Your CHT will be to high, you'll set yourself
up for frequent cylinder overhauls.

I think you might want to have your baffles looked at.
CHT's should not be as big of an issue in a 150 as yours
seem to be.

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: I take off full throttle and then throttle back
: to 2600.
Remember that throttle placement provides limited indication of
power setting at differing altitudes. I have a friend with a Cherokee 140
who says he always cruises at 2400 RPM. I asked what altitude, and he
said *any* altitude. That's a bunch of crap, since at 8000', 2400 RPM is
about 55% power, and the plane's wallowing through the sky.

:The CHT will be around 380 F, below
: the 400 F mark my mechanic advised me not to
: exceed.
This is true. 400 degrees is considered the beginning of the
"bad" area. I put CHT probes in my O-360 lycoming last fall, and was
worried when I routinely saw 400-425. I did a whole bunch of testing,
calibrating, etc to discover that it was because I was using the
spark-plug type probes. The factory-recommended probes are the bayonet
ones, and they read around 50 degrees cooler than the spark plug type. I
actually put 5 CHT probes on my 4 cylinder... one of them is a bayonet one
and does indeed read about 50 cooler than the spark plug ones. Even on a
climbout when I see 425, it's still actually 375 or less.

I don't think the O-200 in your C-150 has bayonet holes. I also
don't know Continental's recommendation on placement and temps. If it is
a spark plug type, however, it's less of a concern.


: With 2600 RPM, I get about 95 knots indicated.
: (My C150 has no wheelpants. Word is, you'll see
: 5 to 10 knots more with wheelpants.)
Slower airspeed give less cooling too.


: Typical cruising altitudes for me are 3500, 4500
: and 5500.
Ah yes... flatlander. At these altitudes, running 2600 RPM is
pretty reasonable "cruise" setting. Probably 75%@3500 and 65%@5500.

:Went to 10500 once, overflying SFO
: class Bravo (full throttle of course), but the CHT
: was slightly over 400 F and this is not the best
: thing to do. I don't think I'll do that again.

A C-150 at 10500? Cool... I know I pretty much *need* full
throttle at those altitudes to keep flying. It's only 20" of MP... the
same as about 2400 RPM @ 5000'.

-Cory

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(Tony Roberts) wrote in message ...
I take off full throttle and then throttle back
to 2600. The CHT will be around 380 F, below
the 400 F mark my mechanic advised me not to
exceed.

What EGT when CHT is 380F ?

I always see around 1450 EGT in cruise, no matter what.
I find the EGT pretty useless.
I know there are wizards who have mastered the art of
leaning ("50 F lean of peak" or whatever is considered
this month's best leaning technique) but I found that
the needles move so slowly that you want to be
glacially slow on the mixture knob and I don't have
the patience for that.

I scan the EGT for unusual temps like 1600 or 1300,
that's all.