REFLECTOR:Rough Rider

Chuck Jensen reflector@tvbf.org
Sun, 20 Jul 2003 11:04:44 -0400


Ronnie, good shot!  That should wake those Franklinsteins up!

-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
Behalf Of Ronnie Brown
Sent: Sunday, July 20, 2003 10:12 AM
To: reflector@tvbf.org
Subject: Re: REFLECTOR:Rough Rider


Another "solution" is to run a small line from the spider to the fuel tank
to allow more cool fuel to circulate and thereby reducing the occurrence of
fuel vaporization.  Modern fuel injected cars do this via a high pressure
regular installed on the engine, and I believe some aviation installations
have this as well. Only problem is, if you have a fuel flow meter, it will
not read correctly unless you subtract the return flow.  And then, you would
be adding one more point of failure and possible fuel leak.  And the fuel
injector servo would probably have to be recalibrated.

I like the rough idle! I paid lots for a hot cam for my Chevy powered 53
Studebaker coupe back in the '60's so it would idle rough at the red lights!
Ah, I knew I should have bought the Franklin!

Ronnie

----- Original Message -----
From: "Chuck Jensen" <cjensen@dts9000.com>
To: <reflector@tvbf.org>
Sent: Sunday, July 20, 2003 10:13 AM
Subject: RE: REFLECTOR:Rough Rider


| I have the top NACA and top fuel spider. It seems logical (another way of
| saying I lack proof of any sort) that the top spider receives ample
cooling
| during flight but after landing, the heat soaked engine, with the sharp
| reduction of air cooling, will start to heat up the fuel lines and result
in
| vaporization of the fuel, particularly around the injectors where there is
a
| direct conduit for the heat from the engine body.
|
| Not having done engine work of this nature, is it a big deal to reposition
| the spider to the underside of the engine?  Or, does it fall under the "if
| its only partly broken, don't fix it?"
|
| In sum, it's really no big deal to run the booster pump on the ground to
| ensure smooth operations.  My greatest concern was whether this was an
early
| indicator of a fuel pump that was going South.  Since it appears the fuel
| pump is probably not a cripple, then the effort to sort it out is just
part
| of the hang-up thing about it "not being right."  However with a top-NACA,
| top-spider installation, this appears to be characteristic behavior and
may
| be a good as it gets.
|
| Chuck
| N27GV
|
| -----Original Message-----
| From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
| Behalf Of Mike Pollock
| Sent: Sunday, July 20, 2003 9:11 AM
| To: reflector@tvbf.org
| Subject: RE: REFLECTOR:Rough Rider
|
|
| We use updraft cooling and we moved the spider to the bottom.  Our engine
| runs smooth even when hot on the ground.  Dwane Swing suggested that we
put
| the spider on the bottom to eliminate just the type of problem that
several
| of the velocity flyers are having with rough running engines when hot.
|
| Mike
|
|
| -----Original Message-----
| From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
| Behalf Of Scott Derrick
| Sent: Saturday, July 19, 2003 9:05 PM
| To: reflector@tvbf.org
| Subject: Re: REFLECTOR:Rough Rider
|
|
| Spider is on top and I'm using updraft cooling. I thought about putting
| a piece of insulation in the bottom side of the spider to keep it
| cooler.  Think it would help?
|
| Scott
|
| Mike Pollock wrote:
| > Is your fuel injector spider on the top of the engine?  Are you using
| > updraft or downdraft configuration?
| >
| > Michael Pollock
| >
| >
| > -----Original Message-----
| > From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
| > Behalf Of Chuck Jensen
| > Sent: Saturday, July 19, 2003 11:26 AM
| > To: 'reflector@tvbf.org'
| > Subject: RE: REFLECTOR:Rough Rider
| >
| >
| > Well, maybe the booster pump is enough to overcome the vaporization in
the
| > injection line because it will run pretty smooth even down to 700 rpm
| after
| > flight, if the booster is run. But won't smoothly at 1100 rpm
wo/booster.
| >
| > I can see how the temp/conditions in the injection lines would be pretty
| > consistent after power operations so the booster pump would have the
same
| > salutory effect after pretty much any flight.
| >
| > Good thought on not increasing the idle speed.  The brakes already have
| > enough work to do without having to overcome a fast idling engine
pushing
| it
| > down the runway on landing.
| >
| > My concern that "this ain't right" grew out of comments from a couple
| > mechanics and a CFI that thought smooth engine ops, even at low rpms,
| should
| > not be dependent on the booster pump.
| >
| > Nonetheless, Scott gets the Southern Comfort(ing)Award, even though I
| still
| > have a tiny bit of residual doubt.
| >
| > Chuck XL/RG
| >
| >
| >
| >
| >
| > -----Original Message-----
| > From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
| > Behalf Of Scott Derrick
| > Sent: Saturday, July 19, 2003 10:54 AM
| > To: reflector@tvbf.org
| > Subject: Re: REFLECTOR:Rough Rider
| >
| >
| > Sounds pretty normal for an injected lycoming.
| >
| > I have a IO360 which isn't the same engine but the injection system is
| > very similar. I also have a Mag/IE combo. My plane runs exactly the
| > same.  Very smooth idle when cold, idles rough as a cob when hot unless
| > I increase the fuel flow to about 5 gph. I can do this using the
| > electric fuel pump or just idle it at 1000 rpm instead of the normal
| > 600-700 which is what I do when hot.  DO NOT increase your idle speed!!
| > Bad idea. You want that low idle speed when landing so you can slow
down.
| >
| > This rough idle is worse in the summer for my plane. Its just the fuel
| > vaporizing in the injection lines, no biggie as it only happens at low
| idle.
| >
| > First time it happened to me I ran to my friend an A&P/IA.  He said, no
| > problemo. Just Lycomings injection system design.
| >
| > Your fuel pressures sound right on to me, I think the other pressures
| > you are referring to were for a Franklin.
| >
| > The A&P that enrichened the idle mixture was probably right in doing so
| > but that won't effect the vaporization of fuel in your injection lines
| > when the cylinders are hot.
| >
| > Sounds like your setup is right on, keep flying!
| >
| > Scott
| >
| >
| > Chuck Jensen wrote:
| >
| >>I have an engine issue that two mechanics have looked at...and that's
all
| >>they've done.  I wondered if anyone has ideas on avenues of
| >>investigation/solution.  I'm running a 540 with mag/EI combo.  The
engine,
| >>particularly after a long flight (less so after starting cold), runs
rough
| >>at ramp speed (1,000 rpm).  Here are the symptoms with a hot engine
after
| >>flight:
| >>
| >>As long as the booster pump is on, runs smooth as glass.  VM-100
indicates
| >>30 psi (from another post, is that way too high??) and approx. 4.0 gph
| >
| > @1000
| >
| >>rpm.  If the booster pump is secured, fuel pressure drops to 28 psi,
fuel
| >>flow shows 1.7 and engine bounces between 650-700 and just barely stays
| >>running.  Turn the boost back on, and it immediately goes back to smooth
| >>operations with the first set of values.  Turn the boost off, and it's
| >
| > right
| >
| >>back in the dumps.
| >>
| >>At cruise or high power operations, the boost pump on/off makes no
| >>difference in fuel pressure, fuel flow or smoothness of operations.
| >>
| >>One mechanic suggested that the idle speed needed to be increased.  ??
| >>Seems he was missing the point.  I'm intentionally setting it at 1,000
rpm
| >>with the booster, then engine goes in the toilet when the booster is
cut.
| >>
| >>The second mechanic increased the richness setting which may have been
too
| >>lean since I did not get a temporary rpm increase when cutting off the
| >>mixture, but the reliance on the booster pump did not change for smooth
| >
| > ramp
| >
| >>operations (especially when hot).
| >>
| >>Induction plenum has been checked thoroughly but that would seem to be
| >>unrelated to the observed symptoms.
| >>
| >>Questions:  1) are my fuel pressure values way out of line (earlier post
| >>talked about 5-6 psi)?  2) if my numbers are bogus, do I
| >>have a bad fuel pressure sensor or ground?
| >> 3) what do others run for fuel pressure/flow at 1,000 rpm on
| >>a 540?
| >> 4) is the main fuel pump going in the crapper? (its been
| >>this way for a long time with no further
| >>degradation/change)
| >> 5) is this type of poor low power performance characteristic
| >>of deterioration of the positive displacement type
| >>fuel pump?
| >> 6) is there a way to check the main fuel pump performance?
| >>
| >>I was in the camp that the main fuel pump is going downhill but I don't
| >>understand why, if it is putting out that much pressure, why the fuel
flow
| >>should fall so much when the booster pump is secured.
| >>
| >>By all rights, these questions should be investigated and fixed by a
good
| >>mechanic (which exempts me), but since that avenue has been
unproductive,
| >
| > I
| >
| >>thought I'd check out the collective wisdom/experience of the
| >
| > Reflectorites.
| >
| >>Best idea wins an official Atta Boy award; redeemable wherever good
ideas
| >>are sold.
| >>
| >>chuck
| >>N27GV
| >>
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| >
| >
| >
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|
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