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320-E2G sump question

 
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jmpcrftr(at)teleport.com
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PostPosted: Sat Feb 11, 2006 6:25 pm    Post subject: 320-E2G sump question Reply with quote

Has anyone successfully made a carbureted O-320 have 100 or less EGT
spread through the full range of the throttle? If so what model
engine and what sump is on the engine?

Carbureted engine, I'm trying to sort out an annoying mixture
distribution (I know.. buy fuel injection). Full throttle is nice
and even, typical 75-100 EGT spread. Just off of full throttle #3 &
4 leans out and #1 & 2 goes rich, typically 275 deg F EGT spread.
Back to 2/3 throttle and on down they even back out again.

Carb is a 10-5009 with the nozzle kit to make it a 10-5217. The kit
was supposed to improve mixture distribution. It didn't.

From the symptoms I can say it's not an induction leak. I'm
wondering if this particular engine with its particular sump and
induction tubes has something to do with it.

The O-320-E2G is listed as having an A sump. I see some references
to a straight riser sump ( -A1B for instance). My O-320-E2G
induction tubes on cylinders 3 & 4 come out from the narrow part of
the sump in the back directly under the lower engine mount. The
four induction tubes don't point directly to the riser where the
carb bolts on.

Thanks in advance for any help or suggestions.
(I know .. get rid of the engine monitor)
Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR
13B in gestation mode, RD-1C, EC-2


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Fred Stucklen



Joined: 10 Jan 2006
Posts: 10
Location: East Windsor, CT

PostPosted: Mon Feb 13, 2006 5:18 am    Post subject: 320-E2G sump question Reply with quote

Michael,

I've been having exactly the same problem with an O-320-D1A that had 9:1
pistons. I've tried rejetting it, even sent the Carb back to Aero Sport
Power. Nothing seems to correct the situation. I did read on the Lycoming
web site last week that this is a common occurrence with Carb'ed engines.
Iv I run the engine at different power settings, I get different EGT's &
CHT's. At 2350 RPM (fixed pitch prop) in cold air (less than 25*F) # 4 CHT
goes so low it will start skipping, especially if I have leaned at all. All
temps are fine at full throttle and at something like 2150 RPM. In warm air
the situation is much less pronounced....
So I've gotten to the point where I ether fly slow in cold air,
(especially down low) or at full throttle, leaned, at high altitudes
(11,000' or more). Sure makes me want to reconsider a fuel injection
system....
I do have all EGT's and CHT's, and have talked to Bart at Aero Sport Power
extensively about this situation. He doesn't have too much to add....
Fred Stucklen
RV-6A N926RV
South Windsor, Ct 06074
phone: (860)727-2393
email: fred.stucklen(at)utcfuelcells.com
Time: 06:25:18 PM PST US
From: Michael McGee <jmpcrftr(at)teleport.com>
Subject: 320-E2G sump question


Has anyone successfully made a carbureted O-320 have 100 or less EGT
spread through the full range of the throttle? If so what model
engine and what sump is on the engine?

Carbureted engine, I'm trying to sort out an annoying mixture
distribution (I know.. buy fuel injection). Full throttle is nice
and even, typical 75-100 EGT spread. Just off of full throttle #3 &
4 leans out and #1 & 2 goes rich, typically 275 deg F EGT spread.
Back to 2/3 throttle and on down they even back out again.

Carb is a 10-5009 with the nozzle kit to make it a 10-5217. The kit
was supposed to improve mixture distribution. It didn't.

From the symptoms I can say it's not an induction leak. I'm
wondering if this particular engine with its particular sump and
induction tubes has something to do with it.

The O-320-E2G is listed as having an A sump. I see some references
to a straight riser sump ( -A1B for instance). My O-320-E2G
induction tubes on cylinders 3 & 4 come out from the narrow part of
the sump in the back directly under the lower engine mount. The
four induction tubes don't point directly to the riser where the
carb bolts on.

Thanks in advance for any help or suggestions.
(I know .. get rid of the engine monitor)
Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR
13B in gestation mode, RD-1C, EC-2


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jlbaker(at)telepath.com
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PostPosted: Mon Feb 13, 2006 9:01 am    Post subject: 320-E2G sump question Reply with quote

Quote:
I've tried rejetting it, even sent the Carb back to Aero
Sport Power. Nothing seems to correct the situation. I did read on
the

Quote:
Lycoming web site last week that this is a common occurrence
with

Quote:
Carb'ed engines.

Not that you may be able to do anything about it, but this sure
sounds like an exhaust scavenging problem. If all the intake runners
are approximately the same length, what is the situation with your
exhaust systems? Is it an issue that a crossover system might cure?
Just a thought.....
Jim Baker
580.788.2779
'71 SV, 492TC
Elmore City, OK


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Dww0708(at)aol.com
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PostPosted: Mon Feb 13, 2006 10:38 am    Post subject: 320-E2G sump question Reply with quote

Just listening in here All carbureted engines should have the distinct
slight rise in RPM just prior to fuel off at Idle RPM. That establishes not
induction leaks and proper idle fuel to air ration. That said better swap your
probe around to establish repeatability of you symptom. Use a remote
pyrometer and be sure that you guages are accurate. The spark plugs are vital,
play musical sparkplug's. Keep a numbering system and vibe ech them to keep
them straight. Plugs should be examined closely for indications as to
combustion quality. Compressions should be with in 80 percent of each other. David


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Fred Stucklen



Joined: 10 Jan 2006
Posts: 10
Location: East Windsor, CT

PostPosted: Tue Feb 14, 2006 4:40 am    Post subject: 320-E2G sump question Reply with quote

Jim,

My RV-6A does use the Vetterman crossover exhaust system.....

Fred Stucklen
RV-6A N926RV



<mailto:jlbaker(at)telepath.com> >

> I've tried rejetting it, even sent the Carb back to Aero
> Sport Power. Nothing seems to correct the situation. I did read on
the
> Lycoming web site last week that this is a common occurrence
with
> Carb'ed engines.

Not that you may be able to do anything about it, but this sure
sounds like an exhaust scavenging problem. If all the intake runners
are approximately the same length, what is the situation with your
exhaust systems? Is it an issue that a crossover system might cure?
Just a thought.....


Jim Baker
580.788.2779
'71 SV, 492TC
Elmore City, OK


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glcasey(at)adelphia.net
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PostPosted: Tue Feb 14, 2006 5:03 am    Post subject: 320-E2G sump question Reply with quote

Quote:


Quote:
Nothing seems to correct the situation. I did read on the Lycoming
web site last week that this is a common occurrence with Carb'ed
engines.
Iv I run the engine at different power settings, I get different
EGT's &
CHT's. At 2350 RPM (fixed pitch prop) in cold air (less than 25*F)
# 4 CHT
goes so low it will start skipping, especially if I have leaned at
all. All
temps are fine at full throttle and at something like 2150 RPM. In
warm air
the situation is much less pronounced....
So I've gotten to the point where I ether fly slow in cold air,
(especially down low) or at full throttle, leaned, at high altitudes
(11,000' or more). Sure makes me want to reconsider a fuel injection
system....
I do have all EGT's and CHT's, and have talked to Bart at Aero
Sport Power
extensively about this situation. He doesn't have too much to add....
Fred Stucklen

One thing that we learned on car engines way back when was that the
carb inlet condition makes a big difference. I've seen some aircraft
installations that were well done except for the carb inlet. Ideally
the inlet should be a bell-mouth (elliptical is a good approximation)
or at least radiused with equal air flow from all directions. Not
easy to do with the tight space constraints that usually exist. One
way to do it that I have looked at (not done as I don't have a carb'd
engine) is to bolt a radius - no duct - to the carb inlet and then
surround the carb with inlet air by building a dam well above the
inlet that extends outward from the carb to the lower cowl. Air can
then flow past the carb and enter the inlet from the rear, balancing
the flow that comes from the front. The lower restriction will give
more power as well. Remember, a sharp-edge inlet will have a Cd of
about 0.6 compared to a radiused inlet that will have a Cd of almost
1.0, meaning the pressure drop at the inlet will be 60% of what it is
with a sharp edge. Might be worth a try.

Another thing we tried was a "dip tube", which is a tube that extends
down (oops, up) into the manifold slightly past where the individual
runners come off the manifold. This creates a sharp edge that
prevents the fuel and/or air from clinging to one side and not the
other. Made a definite improvement and carefully done didn't impede
the air flow too much.

Gary Casey


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Fred Stucklen



Joined: 10 Jan 2006
Posts: 10
Location: East Windsor, CT

PostPosted: Tue Feb 14, 2006 5:21 am    Post subject: 320-E2G sump question Reply with quote

David,

I've calibrated all probes (with a certified calibrations device). All are
within 1% accuracy. The idle cuttoff RPM rise is present (but this should
have no effect on the cruise RPM or cruise mixture problem). I've also tried
a new set of plugs, with exactly the same results.
Just to recap the issue, CHT's & EGt's between cyclinders are diverging
under certainpower settings (10-5217 carbureted O-320-D1A engine with
Vetterman crossover exhaust). Running the engine at low power settings (2100
RPM and lower) and at full power setting results in CHT's & EGT's that are
very similar (CHT's within 5*-10*, EGT's within 50*). Runing the engine
between 2200 - 2440 RPMS (maybe around 90% throttle) results in diverging
CHT's & EGT's, with cylinders #3 & #4 (#4 being the coldest), especially in
cold air (< 25*F) and leaned. #4 CHT will go below 200*F and begin skipping.
The tests I have run seem to indicate that the CHT/EGT divergence is
directly related to the throttle plate position. Try this: pick an altitude
below 8000' where the OTA is 20* or less. Run at 1900 RPM cruise, full rich,
and note all CHT's & EGT's. Be sure to allow time for thermal stabalization.
Repeat the same test at 500 RPM increments, and then at different mixture
settings (witht he 1900 RPM mixture setting as the reference point.).
Normalize the numbers by showing only the differences in temps between the
1900 RPM full rich data, and all other data. Plot out curves of divergence
Vs Throttle position for different mixture settings. (Having a normalized
CHT/EGT gauge helps emmensly in visualizing the resulting divergences...)
What I saw was about the same CHT's/EGT's differences at 1900 RPM and
full throttle, with diverging temps at throttle positions in between those
settings. I have also noted that at higher Outside Air temps, there is a
lesser problem. This might suggest that the fuel atomization at the colder
OAT's is not as complete at is is with higher OAT's. This, coupled with the
throttle plate position, could cause more fuel to be routed into the front
cylinders, with more air going to the back cylinders. (Remember, the
throttle plate position [at less than full throttle] favors flow towards the
front cylinders.)
I would like to try other carburetors to see if there isn't a better
solution. I'm not sure that there are any other carbs out there that will
run OK on this engine.... Another solution might be to put a honey cone type
device between the carb and the sump. This should help straighten out the
air flow....

Fred Stucklen
RV-6A N926RV
430 Hrs




<mailto:Dww0708(at)aol.com>

Just listening in here All carbureted engines should have the
distinct
slight rise in RPM just prior to fuel off at Idle RPM. That
establishes not
induction leaks and proper idle fuel to air ration. That said
better swap your

probe around to establish repeatability of you symptom. Use a remote
pyrometer and be sure that you guages are accurate. The spark plugs
are vital,

play musical sparkplug's. Keep a numbering system and vibe ech them
to keep
them straight. Plugs should be examined closely for indications as
to
combustion quality. Compressions should be with in 80 percent of each
other.
David


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Dww0708(at)aol.com
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PostPosted: Tue Feb 14, 2006 7:21 pm    Post subject: 320-E2G sump question Reply with quote

vetterman? The idle cut off check is kind of an induction tube integitidy
check,it proofs if you have vacuum leaky pipes. Vacuum is strongest at idle
RPMs and a sucking leak will inhibit the proper RPM rise ( lean out ) at Idle
cutoff indicating lean condition. I know Lyc uses an oil heated induction
manifold, Helps atomization. If the carb heat is leaking it can adversely affect
the fuel air ratio. Any way looks like you have been trial and erroring it.
The industry is like that. I am curious, Lyc operators manual? I have
one, the thing that comes to me is what is the manifold pressure doing? Is
there a curve trend that should/would mirror you other parameters? Manifold
pressure at pressure altitude and OAT. Manifold pressure is the power
indicator. Then there is the basic push rod clearance with dry tap it. Very
important to brake horses and volumetric effeciency.Selection of push rod lengths
are how to adjust dry tappet clearance. Some might say that that valve timing
issue would lead to engine roughness and it should but needs confirmed. Very
basic. If I was a Lyc tech rep I would verify all this before before
experimenting away from the basic engine design. Have read about the intake and
exhaust rocker arm movements and making sure consistent to other cylinders. Are
all the correct part number items include in proper engine build up. David


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Fred Stucklen



Joined: 10 Jan 2006
Posts: 10
Location: East Windsor, CT

PostPosted: Wed Feb 15, 2006 5:47 am    Post subject: 320-E2G sump question Reply with quote

David, Gary,

Veternman crossover exhaust: I think his company name is High Mountain
Exhaust.
Standard system for most RV's.....
The idle cutoff test worked fine, with a 100 RPM rise, so I'm sure there
aren't any
intake leaks. I've looked very carefully at all intake components and can't
find any
leaks. I've even performed checks to find cracks (exterior surface powder &
carb
cleaner into intakes/exhaust ports, compression checks, visual checks)....
Trial & Error approach: I'd like to think that I've taken a lot of data
that characterizes
just how the engine is operating. I have documented everything: fuel flow,
manifold
pressure, OAT, EGT, CHT, throttle position, mixture position, RPM, oil temp
&
pressure, etc.... The ONLY relationship to the poor EGT's & CHT's seems to
be
throttle position.
By the way, Bart Lablond (Aero Sport Power) has also looked at this engine
and can't seem to find why it's behaving the way it is..... He ran it in a
test cell, I've
run it in the plane, so the induction system (major difference) might still
be the
culprit.
I have checked the dry tappet clearances and they are within the Lycoming
specs...

Induction System: I'm using Van's standard FAB320 Air box. This is a
snorkel type
airbox that utilizes the lower cowl shape (snorkel) to feed air into a short
snorkel,
then into a larger chamber (much like a car airbox). The air filter is
mounted to
the bottom of the carb (Oval shaped with top/bottom plates). I have tried
to
modify the airflow into the filter box area by placing a wedge in front of
the filter
to divert some of the ram air flow. This didn't seem to help at all.
Since this is the second RV-6A that I've built (the first didn't have
these problems)
I've had a chance to compare the two induction systems. The first RV did
have
a larger volume area around the filter. This probably allowed better
distribution of
the air around the filter. I've ordered a new fiberglass air box part, and
plan on
installing it with modifications that will increase the airbox volume.
(Unfortunately,
Van has made some cowl, and engine mount changes that don't allow for the
use of his original airbox.) The air filter is the same....
I have experimented with the current air box. Putting a hole
in the bottom of the box (allowing air to enter/exit into the lower cowl)
did show
a significant change in the EGT/CHT patterns. The basic problem didn't go
away,
just changed how the engine breaths.
So that is the path that I'm going down next........ A modified airbox to
increase
the volume. I'd also like to run the engine without a filter to see what
happens to
the EGT/CHT patterns at various throttle settings. The filter should
actually result
in better airflows into the carb, but I need to know what it does without
it.

Fred Stucklen
RV-6A N926RV


vetterman? The idle cut off check is kind of an induction tube
integitidy
check,it proofs if you have vacuum leaky pipes. Vacuum is strongest
at idle
RPMs and a sucking leak will inhibit the proper RPM rise ( lean out )
at Idle

cutoff indicating lean condition. I know Lyc uses an oil heated
induction
manifold, Helps atomization. If the carb heat is leaking it can
adversely affect

the fuel air ratio. Any way looks like you have been trial and
erroring it.

The industry is like that. I am curious, Lyc operators manual? I
have
one, the thing that comes to me is what is the manifold pressure
doing? Is

there a curve trend that should/would mirror you other parameters?
Manifold
pressure at pressure altitude and OAT. Manifold pressure is the power

indicator. Then there is the basic push rod clearance with dry tap
it. Very

important to brake horses and volumetric effeciency.Selection of push
rod lengths

are how to adjust dry tappet clearance. Some might say that that
valve timing

issue would lead to engine roughness and it should but needs
confirmed. Very
basic. If I was a Lyc tech rep I would verify all this before before
experimenting away from the basic engine design. Have read about the
intake and

exhaust rocker arm movements and making sure consistent to other
cylinders. Are

all the correct part number items include in proper engine build up.
David


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glcasey(at)adelphia.net
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PostPosted: Wed Feb 15, 2006 6:58 am    Post subject: 320-E2G sump question Reply with quote

A couple more comments:

It looks like you correctly found out that throttle position makes a
difference. Sometimes it is better for the throttle to be full open
and other times it is better with the throttle partly closed or even
past fully open, deflecting the flow the other way. There is nothing
wrong with running with a partially closed throttle as the last maybe
20 degrees of rotation won't give any more air flow anyway.

Another observation - these engines are running in certified aircraft
and from you description I'm sure they don't have the problem - or at
least not so serious as to cause a problem. Since the engine itself
(sump, runners, carb) is of a standard configuration, what else is
different. The engine configuration probably doesn't need fixing.
Some have argued that the exhaust system could play a role, but I
reject that notion as at the rpm you are running there isn't much in
the way of tuning or pulsation effects that will be noticeable.
Also, any cam wear or valve clearance issues will only result in
slight power differences between cylinders, not large mixture
variations.

I still strongly suspect the carb inlet configuration. What is it like?

Gary


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James Baldwin



Joined: 16 Jan 2006
Posts: 23

PostPosted: Wed Feb 15, 2006 9:05 am    Post subject: 320-E2G sump question Reply with quote

Fred -
Sounds like you've zeroed in on your engine's performance pretty
accurately. Before you get your knickers in a real knot, realize you
are collecting data at a level few people do with what production
aircraft your engine is in. My friend and I both had Grumman Cheetahs
with the carburated O320s. He installed the four cyl JPI EGT/CHT probe
system very accurately i.e. all the CHT probes were screw-in and the EGT
probes were positioned as close as possible to be in the same position
relative to the exhaust outlet per JPI install instructions. As an
engineer I was very interested because we were going to really get some
improved BSFC out of these engines. (we thought). Long story short, we
experienced exactly what you are seeing and in my humble opinion, you
will not be able to tighten the observed spread in EGT performance with
respect to throttle position in all cases. That's one reason why the
manufacturers eventually went to the mechanical fuel injection systems
in use today. They can tune each cylinder as if it were an individual
engine and not worry about how the fuel is distributed. Wide open
throttle is what we settled for and used altitude as the variable for
desired percent power. Don't waste any more time, go get some fuel
injection for it and spend your time tuning the injection nozzles to
tighten your EGT spread. Then you can go after fine tuning of the
cooling baffles to even out the CHT spread. JBB

Stucklen, Frederic W UTPWR wrote:

Quote:


David, Gary,

Veternman crossover exhaust: I think his company name is High Mountain
Exhaust.
Standard system for most RV's.....
The idle cutoff test worked fine, with a 100 RPM rise, so I'm sure there
aren't any
intake leaks. I've looked very carefully at all intake components and can't
find any
leaks. I've even performed checks to find cracks (exterior surface powder &
carb
cleaner into intakes/exhaust ports, compression checks, visual checks)....
Trial & Error approach: I'd like to think that I've taken a lot of data
that characterizes
just how the engine is operating. I have documented everything: fuel flow,
manifold
pressure, OAT, EGT, CHT, throttle position, mixture position, RPM, oil temp
&
pressure, etc.... The ONLY relationship to the poor EGT's & CHT's seems to
be
throttle position.
By the way, Bart Lablond (Aero Sport Power) has also looked at this engine
and can't seem to find why it's behaving the way it is..... He ran it in a
test cell, I've
run it in the plane, so the induction system (major difference) might still
be the
culprit.
I have checked the dry tappet clearances and they are within the Lycoming
specs...

Induction System: I'm using Van's standard FAB320 Air box. This is a
snorkel type
airbox that utilizes the lower cowl shape (snorkel) to feed air into a short
snorkel,
then into a larger chamber (much like a car airbox). The air filter is
mounted to
the bottom of the carb (Oval shaped with top/bottom plates). I have tried
to
modify the airflow into the filter box area by placing a wedge in front of
the filter
to divert some of the ram air flow. This didn't seem to help at all.
Since this is the second RV-6A that I've built (the first didn't have
these problems)
I've had a chance to compare the two induction systems. The first RV did
have
a larger volume area around the filter. This probably allowed better
distribution of
the air around the filter. I've ordered a new fiberglass air box part, and
plan on
installing it with modifications that will increase the airbox volume.
(Unfortunately,
Van has made some cowl, and engine mount changes that don't allow for the
use of his original airbox.) The air filter is the same....
I have experimented with the current air box. Putting a hole
in the bottom of the box (allowing air to enter/exit into the lower cowl)
did show
a significant change in the EGT/CHT patterns. The basic problem didn't go
away,
just changed how the engine breaths.
So that is the path that I'm going down next........ A modified airbox to
increase
the volume. I'd also like to run the engine without a filter to see what
happens to
the EGT/CHT patterns at various throttle settings. The filter should
actually result
in better airflows into the carb, but I need to know what it does without
it.

Fred Stucklen
RV-6A N926RV


vetterman? The idle cut off check is kind of an induction tube
integitidy
check,it proofs if you have vacuum leaky pipes. Vacuum is strongest
at idle
RPMs and a sucking leak will inhibit the proper RPM rise ( lean out )
at Idle

cutoff indicating lean condition. I know Lyc uses an oil heated
induction
manifold, Helps atomization. If the carb heat is leaking it can
adversely affect

the fuel air ratio. Any way looks like you have been trial and
erroring it.

The industry is like that. I am curious, Lyc operators manual? I
have
one, the thing that comes to me is what is the manifold pressure
doing? Is

there a curve trend that should/would mirror you other parameters?
Manifold
pressure at pressure altitude and OAT. Manifold pressure is the power

indicator. Then there is the basic push rod clearance with dry tap
it. Very

important to brake horses and volumetric effeciency.Selection of push
rod lengths

are how to adjust dry tappet clearance. Some might say that that
valve timing

issue would lead to engine roughness and it should but needs
confirmed. Very
basic. If I was a Lyc tech rep I would verify all this before before
experimenting away from the basic engine design. Have read about the
intake and

exhaust rocker arm movements and making sure consistent to other
cylinders. Are

all the correct part number items include in proper engine build up.
David








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GrummanDude



Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

PostPosted: Wed Feb 15, 2006 10:28 am    Post subject: 320-E2G sump question Reply with quote

In a message dated 2/15/06 7:00:44 AM, glcasey(at)adelphia.net writes:
Quote:
There is nothing=A0
wrong with running with a partially closed throttle as the last maybe=A0
20 degrees of rotation won't give any more air flow anyway.


Not sure if you've tried this, (I haven't read all of the emails) but, try a
little carb heat at different throttle positions. I have an O360 with the
JPI 800. Carb heat has shown to move the EGT spread around at different
throttle settings.


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AuCountry Aviation
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jlbaker(at)telepath.com
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PostPosted: Wed Feb 15, 2006 4:26 pm    Post subject: 320-E2G sump question Reply with quote

Quote:
That's one reason why the manufacturers eventually went to the
mechanical fuel injection systems in use today. They can tune
each

Quote:
cylinder as if it were an individual engine and not worry about how
the fuel is distributed. >


Well, that's partly true. FI is a whole lot better than carburetion in
terms of getting the right amount to each port.....avoiding having it
robbed from one port to someplace in the induction runner or to
another intake port is still a problem. I see about 125F difference
from top to bottom on my IO520. Unless you can do direct injection,
there's always some interference in the process at some given
RPM(s).
Jim Baker
580.788.2779
'71 SV, 492TC
Elmore City, OK


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James Baldwin



Joined: 16 Jan 2006
Posts: 23

PostPosted: Wed Feb 15, 2006 4:59 pm    Post subject: 320-E2G sump question Reply with quote

Jim -
The Cont 520 series is well known for its air/fuel mixture distribution
problem. That of course is what the calibrated injector nozzles from
George Braly at GAMI are all about. Are you using the GAMI nozzles in
your airplane? The A36 with the Tornado Alley Turbo normalizer I fly
has them and the spread is minimal and lean of peak cruise is very
smooth and economical. I don't have the spread at my fingertips here
because I actually only monitor TIT during operation. JBB

Jim Baker wrote:

Quote:




>That's one reason why the manufacturers eventually went to the
>mechanical fuel injection systems in use today. They can tune
>
>
each


>cylinder as if it were an individual engine and not worry about how
>the fuel is distributed. >
>
>
Well, that's partly true. FI is a whole lot better than carburetion in
terms of getting the right amount to each port.....avoiding having it
robbed from one port to someplace in the induction runner or to
another intake port is still a problem. I see about 125F difference
from top to bottom on my IO520. Unless you can do direct injection,
there's always some interference in the process at some given
RPM(s).
Jim Baker
580.788.2779
'71 SV, 492TC
Elmore City, OK









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flyv35b(at)ashcreekwirele
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PostPosted: Wed Feb 15, 2006 6:09 pm    Post subject: 320-E2G sump question Reply with quote

It's not the absolute EGT or even the difference from one cylinder to
another that is the most important, but whether or not all cylinders reach
peak EGT at close to the same time and mixture control position. Granted,
this will change with throttle position and rpm and maybe other things but
if the spread in fuel flow from the first cylinder to reach peak to the last
is about .25 gph (on an IO-520 say) then you have a pretty even mixture
distribution and the engine will run smooth on the lean side of peak EGT.
You can have 2 different cylinders that are 50F or more apart temperature
wise but reach peak EGT at the very same time. The GAMI injectors taylor
the fuel flow to match the uneven airflow distribution and thereby hopefully
have all cylinders reach peak EGT at close to the same time.

Cliff
---


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James Baldwin



Joined: 16 Jan 2006
Posts: 23

PostPosted: Wed Feb 15, 2006 6:24 pm    Post subject: 320-E2G sump question Reply with quote

Yes.
flyv35b wrote:

[quote]

It's not the absolute EGT or even the difference from one cylinder to
another that is the most important, but whether or not all cylinders reach
peak EGT at close to the same time and mixture control position. Granted,
this will change with throttle position and rpm and maybe other things but
if the spread in fuel flow from the first cylinder to reach peak to the last
is about .25 gph (on an IO-520 say) then you have a pretty even mixture
distribution and the engine will run smooth on the lean side of peak EGT.
You can have 2 different cylinders that are 50F or more apart temperature
wise but reach peak EGT at the very same time. The GAMI injectors taylor
the fuel flow to match the uneven airflow distribution and thereby hopefully
have all cylinders reach peak EGT at close to the same time.

Cliff
---


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Dww0708(at)aol.com
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PostPosted: Wed Feb 15, 2006 8:09 pm    Post subject: 320-E2G sump question Reply with quote

sounds like pretty good scoop.... no irregularity intended David

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jlbaker(at)telepath.com
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PostPosted: Wed Feb 15, 2006 9:14 pm    Post subject: 320-E2G sump question Reply with quote

Quote:
That of course is what the calibrated injector
nozzles from George Braly at GAMI are all about. Are you using
the

Quote:
GAMI nozzles in your airplane?

Well, that's the sad part. I live about 30 miles from Ada, OK and the
GAMI folks, have been over there several times watching installs
and test cell runs, but no, I don't because the cost/benefit for me
would be marginal.....except I really like the idea of LOP operation. A
GAMI install would first necessitate a JPI install as well. $$$$$

Sigh.....

Jim Baker
580.788.2779
'71 SV, 492TC
Elmore City, OK


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