Today's Message Index:
----------------------
1. 03:13 AM - leaning (greg and lisa walsh)
2. 07:07 AM - Re: leaning (flyv35b)
3. 09:09 AM - Re: leaning (Aucountry@aol.com)
4. 09:20 AM - Re: leaning (Ron Levy)
5. 09:28 AM - Re: leaning (Ron Levy)
6. 10:31 AM - Re: leaning (flyv35b)
7. 11:13 PM - Tiger, LoPresti nose bowl update (Aucountry@aol.com)
Message 1
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--> TeamGrumman-List message posted by: "greg and lisa walsh" <glwalsh@optusnet.com.au>
am the owner of grumman cheetah....VH. FXV in adelaide/sth australia
i would like to know the best method of leaning..
1]in cruise
2]in climb
3] taxying
the aircraft has a tendecy towards plug fouling. many thanks
greg walsh
Message 2
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--> TeamGrumman-List message posted by: "flyv35b" <flyv35b@juno.com>
> am the owner of grumman cheetah....VH. FXV in adelaide/sth australia
> i would like to know the best method of leaning..
>
> 1]in cruise
> 2]in climb
> 3] taxying
> the aircraft has a tendecy towards plug fouling. many thanks
> greg walsh
>
If you have 80 octane fuel available by all means use it instead of 100LL as
the Cheetah engine does not like the extra lead in 100LL. You will have to
clean the plugs every 50 hrs even if you lean properly. I'd recommend the
REM40E plugs. Unleaded autofuel will solve the problem if you have and can
legally use the STC. Every once in awhile run a tank of leaded Avgas
through it.
1. Lean until the engine just barely starts to run rough and then enrichen
until it smooths out, maybe 2 clicks or maybe only one. This assumes you
are at a power setting of 75% or less.
2. Climb full rich until about 2000-3000ft. and then lean until you get max
rpm or best power.
3. Lean until the engine starts to die and then enrich the mixture just
enough to make it run ok.
These are my recommendations and have worked pretty well for me but are not
exactly what Lycoming recommends. With 100LL fuel in the low compression
engine there is essentially nothing you can do with regard to leaning that
will cause detonation or serious harm to the engine IMO.
Cliff A&P/IA
----- Original Message -----
From: "greg and lisa walsh" <glwalsh@optusnet.com.au>
Subject: TeamGrumman-List: leaning
> --> TeamGrumman-List message posted by: "greg and lisa walsh"
<glwalsh@optusnet.com.au>
>
> am the owner of grumman cheetah....VH. FXV in adelaide/sth australia
> i would like to know the best method of leaning..
>
> 1]in cruise
> 2]in climb
> 3] taxying
> the aircraft has a tendecy towards plug fouling. many thanks
> greg walsh
>
>
Message 3
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--> TeamGrumman-List message posted by: Aucountry@aol.com
In a message dated 10/15/03 03:13:49 AM, glwalsh@optusnet.com.au writes:
> am the owner of grumman cheetah....VH. FXV in adelaide/sth australia
> i would like to know the best method of leaning..
>
> 1]in cruise
> 2]in climb
> 3] taxying
> the aircraft has a tendecy towards plug fouling.=A0 many thanks
> greg walsh
>
Do youhave a 4-cyl CHT/EGT?
Message 4
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--> TeamGrumman-List message posted by: Ron Levy <rblevy@mindspring.com>
From: flyv35b <flyv35b@juno.com>
--> TeamGrumman-List message posted by: "flyv35b" <flyv35b@juno.com>
> i would like to know the best method of leaning..
>
> 1]in cruise
> 2]in climb
> 3] taxying
> the aircraft has a tendecy towards plug fouling. many thanks
Not surprising if you're not leaning hard.
>1. Lean until the engine just barely starts to run rough and then enrichen
>until it smooths out, maybe 2 clicks or maybe only one. This assumes you
>are at a power setting of 75% or less.
2. Climb full rich until about 2000-3000ft. and then lean until you get max
rpm or best power.
3. Lean until the engine starts to die and then enrich the mixture just
enough to make it run ok.
These are my recommendations and have worked pretty well for me but are not
exactly what Lycoming recommends. With 100LL fuel in the low compression
engine there is essentially nothing you can do with regard to leaning that
will cause detonation or serious harm to the engine IMO.
Cliff A&P/IA
----- Original Message -----
From: "greg and lisa walsh" <glwalsh@optusnet.com.au>
Subject: TeamGrumman-List: leaning
> --> TeamGrumman-List message posted by: "greg and lisa walsh"
<glwalsh@optusnet.com.au>
>
> am the owner of grumman cheetah....VH. FXV in adelaide/sth australia
> i would like to know the best method of leaning..
>
> 1]in cruise
> 2]in climb
> 3] taxying
> the aircraft has a tendecy towards plug fouling. many thanks
> greg walsh
>
>
Message 5
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--> TeamGrumman-List message posted by: Ron Levy <rblevy@mindspring.com>
From: flyv35b <flyv35b@juno.com>
--> TeamGrumman-List message posted by: "flyv35b" <flyv35b@juno.com>
> i would like to know the best method of leaning..
>
> 1]in cruise
> 2]in climb
> 3] taxying
> the aircraft has a tendecy towards plug fouling. many thanks
Not surprising if you're not leaning hard.
>1. Lean until the engine just barely starts to run rough and then enrichen
>until it smooths out, maybe 2 clicks or maybe only one. This assumes you
>are at a power setting of 75% or less.
That's good advice. That will put you pretty close to peak EGT, and somewhat lean
of peak CHT, which for these purposes is the best place to be.
>2. Climb full rich until about 2000-3000ft. and then lean until you get max
>rpm or best power.
I think that's shaky advice unless you have all-cylinder CHT gauges to ensure you're
not overtemping the cylinders. At full power and low speed, there's just
enough airflow to carry the heat away with the mixture full rich. By leaning
in the climb at 2000-3000 feet, you're increasing engine temps without increasing
cooling air flow, and that presses the edges of the envelope. Yes, at 2500
you are no longer developing full power, but you're still developing more
than Lycoming is happy to buy off on leaning. If you can monitor CHT on all cylinders,
and ensure that you do not get above 430F (generally recommended max
in climb for best engine life), then it's OK. Without a means to monitor CHT,
I think leaning at full throttle below 5000 DA is Russian Roulette with your
valve guides.
>3. Lean until the engine starts to die and then enrich the mixture just
>enough to make it run ok.
Good words. And after landing, do a lead scavenging run before shutdown. Enrich
enough to run up to 1800 and then lean to peak RPM. Hold it there for 60 seconds
(stock Cheetah engine) or 20 seconds (HC Cheetah engine), then reduce to
1200 and cut the mixture. This will help the heat-activated lead scavenging
agents in the fuel strip some of the lead off the inside of the cylinders, plugs,
piston faces, etc.
Ron
Message 6
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--> TeamGrumman-List message posted by: "flyv35b" <flyv35b@juno.com>
> >2. Climb full rich until about 2000-3000ft. and then lean until you get
max
> >rpm or best power.
>
> I think that's shaky advice unless you have all-cylinder CHT gauges to
ensure you're not overtemping the cylinders. At full power and low speed,
there's just enough airflow to carry the heat away with the mixture full
rich. By leaning in the climb at 2000-3000 feet, you're increasing engine
temps without increasing cooling air flow, and that presses the edges of the
envelope. Yes, at 2500 you are no longer developing full power, but you're
still developing more than Lycoming is happy to buy off on leaning. If you
can monitor CHT on all cylinders, and ensure that you do not get above 430F
(generally recommended max in climb for best engine life), then it's OK.
Without a means to monitor CHT, I think leaning at full throttle below 5000
DA is Russian Roulette with your valve guides.
I guess I can't argue with the comment about monitoring cylinder head
temperatures AND I did mention that these were my comments and not
necessarily what Lycoming recommends. However, I think that most O-320
engines in the Traveler and Cheetah have adequate cooling if the baffles are
in good condition and CHTs do not run so hot as to be of a real concern
(probably not true for the Tiger). Of course without CHT instrumentation
you do not know that. I do think that if you don't do any leaning until you
reach 5000 ft. the engine is running way to rich and that is not desireable
in my opinion. A very good reason to install a 4 cylinder CHT instrument
and possibly 4 cyl. EGT as well.
Cliff A&P/IA
----- Original Message -----
From: "Ron Levy" <rblevy@mindspring.com>
Subject: Re: TeamGrumman-List: leaning
> --> TeamGrumman-List message posted by: Ron Levy <rblevy@mindspring.com>
>
> From: flyv35b <flyv35b@juno.com>
>
> --> TeamGrumman-List message posted by: "flyv35b" <flyv35b@juno.com>
> > i would like to know the best method of leaning..
> >
> > 1]in cruise
> > 2]in climb
> > 3] taxying
> > the aircraft has a tendecy towards plug fouling. many thanks
>
> Not surprising if you're not leaning hard.
>
> >1. Lean until the engine just barely starts to run rough and then
enrichen
> >until it smooths out, maybe 2 clicks or maybe only one. This assumes you
> >are at a power setting of 75% or less.
>
> That's good advice. That will put you pretty close to peak EGT, and
somewhat lean of peak CHT, which for these purposes is the best place to be.
>
> >2. Climb full rich until about 2000-3000ft. and then lean until you get
max
> >rpm or best power.
>
> I think that's shaky advice unless you have all-cylinder CHT gauges to
ensure you're not overtemping the cylinders. At full power and low speed,
there's just enough airflow to carry the heat away with the mixture full
rich. By leaning in the climb at 2000-3000 feet, you're increasing engine
temps without increasing cooling air flow, and that presses the edges of the
envelope. Yes, at 2500 you are no longer developing full power, but you're
still developing more than Lycoming is happy to buy off on leaning. If you
can monitor CHT on all cylinders, and ensure that you do not get above 430F
(generally recommended max in climb for best engine life), then it's OK.
Without a means to monitor CHT, I think leaning at full throttle below 5000
DA is Russian Roulette with your valve guides.
>
> >3. Lean until the engine starts to die and then enrich the mixture just
> >enough to make it run ok.
>
> Good words. And after landing, do a lead scavenging run before shutdown.
Enrich enough to run up to 1800 and then lean to peak RPM. Hold it there
for 60 seconds (stock Cheetah engine) or 20 seconds (HC Cheetah engine),
then reduce to 1200 and cut the mixture. This will help the heat-activated
lead scavenging agents in the fuel strip some of the lead off the inside of
the cylinders, plugs, piston faces, etc.
>
> Ron
>
>
Message 7
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| Subject: | Tiger, LoPresti nose bowl update |
--> TeamGrumman-List message posted by: Aucountry@aol.com
I posted that I was redoing the baffles on a Tiger with the LoPresti nose
bowl. The Tiger owner wanted the nose bowl because she had heard the LoPresti
nose bolw would cure the high CHTs. After the installation, according to her,
the CHTs climbed higher, faster than with the stock nose bowl. So, she flew
it to Fox to have me look at it.
To say the baffles, both the baffles themselves, and the baffle seals, were
in terrible shape to begin with, would be kind. Someone had installed a
lightweight starter and BENT the baffle out of the way (toward the rear) and the
starter had nearly cut a half moon shape out where it hit. Two metal baffle
peices (that wrap around the bottom of the cylinder) were missing. Plus, the
shape of the LoPresti nose bowl makes it very difficult to property seal in the
corners, Upper left and Upper right. The baffle seal tucks in nicely around
the inlet on a stock nosebowl, The seal just hangs there on the LoPresti
without some creative sealing.
I flew the plane today. Max CHT went from 465 to 427. This is pretty
typical even with a stock cowling if you know what you're doing with the baffles.
Fred Geller. Bring your Tiger back. I know how to get theose temps down.
Gary
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