Today's Message Index:
----------------------
1. 07:01 AM - 447 analysis (David Kulp)
2. 07:50 AM - Re: 447 analysis (lucien)
3. 04:38 PM - Re: 447 analysis (Richard Girard)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
A question for the experts. I have a 447 on a Kolb FireFly and have
been unable to get the engine to settle in mid-range RPMs. If I have
the throttle set at a certain point the engine runs strong at 5400Rs,
but when I try to decrease the Rs to about 48-5000, the smallest
reduction causes the engine to slow to about 4300.
I pulled the plugs after landing yesterday and the front cylinder's plug
is an even tan color, but the rear plug is the same tan on half of the
electrode and ceramic cone and sooty black on the other half. First
thing that comes to mind is a leaking head gasket, but also wonder if I
should check the torque on the head bolts first, and has anyone ever
heard of a spark plug "leak" - either the gasket or the plug itself?
Further info that may or may not be pertinent, my CHT gauges show one
cylinder in normal heat range and the other is rather chilly. Checking
this out a while back I checked the temp of the plugs and the heads with
a laser thermometer and they were withing a few degrees of each other,
so I attributed the difference to the gauge or the thermocouple. But
maybe it has something to do with the Blackie Carbon lurking on half my
rear cylinder plug.
Any thought from the experts on the list will be greatly appreciated.
Dave Kulp
Bethlehem, PA
FireFly 11DMK
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 447 analysis |
undoctor wrote:
> A question for the experts. I have a 447 on a Kolb FireFly and have
> been unable to get the engine to settle in mid-range RPMs. If I have
> the throttle set at a certain point the engine runs strong at 5400Rs,
> but when I try to decrease the Rs to about 48-5000, the smallest
> reduction causes the engine to slow to about 4300.
>
> I pulled the plugs after landing yesterday and the front cylinder's plug
> is an even tan color, but the rear plug is the same tan on half of the
> electrode and ceramic cone and sooty black on the other half. First
> thing that comes to mind is a leaking head gasket, but also wonder if I
> should check the torque on the head bolts first, and has anyone ever
> heard of a spark plug "leak" - either the gasket or the plug itself?
>
> Further info that may or may not be pertinent, my CHT gauges show one
> cylinder in normal heat range and the other is rather chilly. Checking
> this out a while back I checked the temp of the plugs and the heads with
> a laser thermometer and they were withing a few degrees of each other,
> so I attributed the difference to the gauge or the thermocouple. But
> maybe it has something to do with the Blackie Carbon lurking on half my
> rear cylinder plug.
>
> Any thought from the experts on the list will be greatly appreciated.
>
> Dave Kulp
> Bethlehem, PA
>
> FireFly 11DMK
Yeah, both of my 447's did this. My single carb 503 did it also tho to a lesser
degree. I think it's just a property of the single carb configuration, but what
the exact cause is I couldn't say.
There's not a whole lot you can do about it, really. One thing that seemed to help
on my engines was varying the load in the spot where it tended to wander.
I.e. add a little pitch (or just fly slower) to load the engine a bit more. This
will require opening the throttle a little more which may get it out of that
wandering range (that worked on my old 447 equipped trike) and make it settle
down.
I also tried different needle settings on the theory that it was lean in that spot.
Raising the needle one notch helped with the hair-trigger throttle on my
trike's 447, but it also made it so rich it stumbled and burbled a little bit.
That was more objectionable to me than the wandering so I set it back where it
was.
It sounds like your EGT's are actually a little cool in that range which could
be either a little rich or too much load (or both).
The really expensive option is to go with the dual-carb setup, if you can still
get the little Bing carbs and manifolds for this. This will completely eliminate
the problem (or at least it did on a friend of mine's Starlight/447), but
it may be too pricey and difficult to make it worth it.
I just learned to live with it myself, generally by just flying slower and loading
the engine a little more when in that particular throttle range....
LS
--------
LS
Titan II SS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=309284#309284
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 447 analysis |
David, A little info please. Is this problem a sudden onset or did it happen
gradually?
Did the engine sit awhile in storage?
Is there any crud in the carb float bowl.
Have you checked the carb socket for cracks?
How is your prop set? What RPM do you get static? What RPM do you get at WOT
in straight and level flight?
Rick Girard
On Wed, Aug 18, 2010 at 9:00 AM, David Kulp <undoctor@ptd.net> wrote:
>
> A question for the experts. I have a 447 on a Kolb FireFly and have been
> unable to get the engine to settle in mid-range RPMs. If I have the
> throttle set at a certain point the engine runs strong at 5400Rs, but when I
> try to decrease the Rs to about 48-5000, the smallest reduction causes the
> engine to slow to about 4300.
>
> I pulled the plugs after landing yesterday and the front cylinder's plug is
> an even tan color, but the rear plug is the same tan on half of the
> electrode and ceramic cone and sooty black on the other half. First thing
> that comes to mind is a leaking head gasket, but also wonder if I should
> check the torque on the head bolts first, and has anyone ever heard of a
> spark plug "leak" - either the gasket or the plug itself?
>
> Further info that may or may not be pertinent, my CHT gauges show one
> cylinder in normal heat range and the other is rather chilly. Checking this
> out a while back I checked the temp of the plugs and the heads with a laser
> thermometer and they were withing a few degrees of each other, so I
> attributed the difference to the gauge or the thermocouple. But maybe it
> has something to do with the Blackie Carbon lurking on half my rear cylinder
> plug.
>
> Any thought from the experts on the list will be greatly appreciated.
>
> Dave Kulp
> Bethlehem, PA
>
> FireFly 11DMK
>
>
--
Zulu Delta
Mk IIIC
582 Gray head
4.00 C gearbox
3 blade WD
Thanks, Homer GBYM
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|