X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mailout1.pacific.net.au ([61.8.0.84] verified) by logan.com (CommuniGate Pro SMTP 4.3.6) with ESMTP id 612955 for flyrotary@lancaironline.net; Sat, 23 Jul 2005 17:51:45 -0400 Received-SPF: none receiver=logan.com; client-ip=61.8.0.84; envelope-from=leonp@pacific.net.au Received: from mailproxy1.pacific.net.au (mailproxy1.pacific.net.au [61.8.0.86]) by mailout1.pacific.net.au (8.13.4/8.13.4/Debian-3) with ESMTP id j6NLoxCh021647 for ; Sun, 24 Jul 2005 07:50:59 +1000 Received: from ar1 (ppp284B.dyn.pacific.net.au [61.8.40.75]) by mailproxy1.pacific.net.au (8.13.4/8.13.4/Debian-3) with SMTP id j6NLonHU030024 for ; Sun, 24 Jul 2005 07:50:49 +1000 Message-ID: <002401c58fd0$4ff1e6b0$4b28083d@ar1> From: "Leon Promet" To: "Rotary motors in aircraft" References: Subject: FUEL FLOW was Re: [FlyRotary] Lycoming debugging test - -HELP! Date: Sun, 24 Jul 2005 07:48:49 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0021_01C59024.20A98490" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 This is a multi-part message in MIME format. ------=_NextPart_000_0021_01C59024.20A98490 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hey Kevin, Check your fuel FLOW RATE, especially at your normal climb angle (on = the ground). It sounds like it's losing fuel flow on take-off - the = carb is using whatever fuel is in the bowl, and then running lean. You = might have to jack the fuselage to the required angle in case there is = something in the tank that is occuding the pick-up(s). However, if you = can reproduce it on the ground doing a run-up, it definitely sounds = like lack of fuel FLOW (not pressure) to me. If the engine will = maintain 1700 RPM, then it is getting almost but not quite enough fuel = FLOW at WOT. Various things come to mind. FIrstly, (and most easily), a partially = blocked fuel filter (just because it's new doesn't mean it'll work!!). = So change that first. Use a different brand to eliminate faulty batch = manufacture.=20 I once had a mysterious problem with an RX4. Chased it for weeks. = Turned out to be a bee in the fuel line. (I'm serious - the guy who = owned the car used to work for me and is still around and will verify = this!!). Anyway, Jack's pride & joy would work just fine around town. = But out on the open road, it would run out of fuel in 3rd gear (usually = when overtaking). Turned out that a bee (very dead at this stage) had = got into the fuel tank. (The problem occurred soon after Jack filled up = at some outback petrol station when he was on holidays). The bee = immediately got stuck in the fuel supply line. At normal cruising flow = rates, there was sufficient fuel to run the car. On hard acceleration, = the bee's wings & body would PARTIALLY block the supply line in the = tank. We only found it when we removed the tank, replaced it with = another one, and cut the old one open. You just wouldn't read about it = in Ripley's or the War Cry! I've also had pieces of fuel gum (and one instance a piece of cardboard) = block the fuel pick-up. When fuel sits a long time at a bowser storage = tank, especially if there is water at the bottom of the tank, it will = form a sheet of gum at the fuel/water interface, almost like condom = latex, (but nowhere near as strong). This film of gum gets broken up = the next time a tanker does a dump, and bits of this will very = effectively block a fuel pick-up, or cripple a fuel filter. =20 I've seen it happen on several occasions over the years. It was = particularly prevalent in the early '70s during the phase out of = "standard" petrol before the introduction of unleaded into this country = (all rotaries used to run on standard not super - which was heavily = leaded back then). I found out the hard way soon after I had purchsed = my RX2 Coupe in 1971. Filled up at an "out of the way" petrol station = (where the fuel sales volume on standard was virtually nil), and = immediately had problems. After eventually getting back to Sydney, we = quickly diagnosed it as a tank problem. Even steam cleaning the tank = didn't fix it. The tank was replaced, and we cut open the old one, = and there was all these bits of gum, just like a thin membrane tyhat = had been cut up. So the place I'd be looking is in your fuel SUPPLY system, as it seems = you have done everything else except check fuel FLOW rate. Can't = guarantee that this IS the problem, but the quick and easy way would be = to check your open flow rate at the carb, and then compare it with = somebody else's. Alternatively, you can work backwards as you know = that the engine requires at least 0.55 Lbs per hour per BHP at WOT. = (First convert that to litres or pints or quarts per minute and you can = direct measure it, or run the fuel into a can for 1 minute and then go = and weigh it). Fuel flow rate should be at least 25% more than the max = required at WOT so that your carb doesn't run dry. One other area of the problem could be the incorrect needle/seat = arrangement on the carb, or a partially blocked filter at the banjo - = I'm not privvy to what carb you are running so this is conjectural as I = plead total ignorance of Lycoming carbs. However, all stock Mazda = carbs have fine brass gauze mesh filters, both at the banjo, and on = top of the needle& seats. Additionally, in the racing 13Bs, an IDA Weber would run out of fuel as = the float bowl was just way too small for anything over 250 BHP. We = used to replace the 2.5 needle/seat assys with 3.0 units. But we would = STILL run out of fuel on long straights. Extended float bowls were then = added, which did fix the problem, but welding the Weber material was = tricky, especially if it had been saturated with oil laced fuel for a = long time (sometimes the castings were slightly porous).. My final solution was to add an EXTRA float bowl (from an SU carb), = with it's own needle & seat, and a fuel return. We could then go back = to a 2.5 Weber needle & seat, as the 3.0 one was prone to flooding at = idle and on the over-run. (Nothing good has ever come of fuel dilition = of engine oil in a race engine). This fixed all fuel flow issues. Some = time later, affordable aftermarket EFI came along, and all this passed = into history. But fuel SUPPLY issues are even MORE critical with EFI. So these are just a few areas where you can look. Be systematic, and = start at the connection between the carb and the supply line. You will = then quickly eliminate either the supply to the carb, or the carb = needle & seat itself. If the open pipe fuel flow is more than adequate, = then I'd be looking inside the carb for restrictions. As I have said, = this is only a guide. Feel free to contact me off line if you feel the = need. Cheers, Leon ----- Original Message -----=20 From: kevin lane=20 To: Rotary motors in aircraft=20 Sent: Sunday, July 24, 2005 6:33 AM Subject: [FlyRotary] Lycoming debugging test - -HELP! I realize that this isn't exactly the right forum, but you guys seem = to have excellent debugging skills. my local RV group is totally = worthless ("I find the carnauba wax doesn't show fingerprints as much as = the....")(except Mike!) the on-field mechanics are sick of me coming = by. my O-320 RV-6A is having RAG (rpm attention getter) problems. it = runs fine until about 300' on take-off, then the rpm's drop to like 1700 = (from 2200). switching mags to electronic ignition(Rose) makes no = difference. mixture no diff. pulling the throttle it will seem to run = fine at 1700rpm. I have 4 new cyls that I am attempting to break in. = ground run ups can only go like 2 minutes before CHT's exceed 400 = degrees. I discovered I can get the rpm drop on the ground if I run it = a minute or so full power. cht's will typically approach 415 degrees = when the drop takes place. I don't know if the temp is significant or = not, it does seem that way. I have a brand new slick left mag. rose = checked the electronic ignition and could find nothing wrong, even put = it in an oven to test. I installed a new carb since the old one showed = signs of leakage (and I'm at whits end). no change. my fuel pressure = has been showing 8psi this last year, up from 6 psi when originally = installed.(no idea why) I installed a pressure regulator in-line which = works like a charm. I can dial whatever pressure I like. 2 psi makes = no difference. I bypassed the mechanical fuel pump and ran it just on = the facet electric. 2 psi, no difference. I discovered that you can run = the carb for maybe 30 secs with no fuel pressure while it burns off the = bowl gas. premier engines suggested induction leak making the engine run = lean. no leaks detected cold or hot engine. (pressurized intake with = vacuum, sprayed soapy water) if the engine didn't run right to start with then many = explanations would hold. but it runs fine for several minutes. it runs = the same under mag or electronic ignition both before and after the = problem kicks in. everyone really wants to blame the rose ignition, but = I'm not seeing any connection. with such a quick run-up my oil temp = barely registers, so I doubt parts are seizing. I have new mineral oil = in it for breakin right now. there is a bit of MMO in the fuel too I = believe, left over from a mechanics "what the hell" attempt from way = back. my cyls are all new, rebuilts, so no valve problems. I checked = the push rod lengths when I reinstalled them. the engine isn't missing = when the problems occurs, it simply won't run faster and it seems to = prefer the throttle pulled back to match the rpm it is putting out. I = can't figure out any more lean mixture scenarios to try. the new carb = runs just like the old one did. I recently replaced the mag harness = with a much newer, used one. I tested it and it was fine. the plugs = are all new, but again, no diff between mag and elec ignition. if I = flip the ignition to R and shut off the elect ig then the engine quits = as would be expected, no wiring problems. fuel, spark, air, timing, that's all there is. this damn lycoming = lawn mower has me stumped. my engine has been running fine up until = this (hey, we all have "cracked" cylinders, get out your microscope and = look!). you guys have any ideas? Kevin Lane Portland, OR e-mail-> n3773@comcast.net ----- Original ------=_NextPart_000_0021_01C59024.20A98490 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hey Kevin,
 
Check your fuel FLOW RATE,  = especially at your=20 normal climb angle  (on the ground).  It sounds like it's losing fuel flow on take-off = - the carb is=20 using whatever fuel is in the bowl,  and then = running lean. You=20 might have to jack the fuselage to the required angle in case there is = something=20 in the tank that is occuding the pick-up(s).  However,  if you = can=20 reproduce it on the ground doing a run-up,  it definitely sounds = like lack=20 of fuel FLOW (not pressure) to me.  If the engine will maintain = 1700=20 RPM,  then it is getting almost but not quite enough fuel FLOW at=20 WOT.
 
Various things come to mind.  = FIrstly, =20 (and most easily),  a partially blocked fuel filter (just because = it's new=20 doesn't mean it'll work!!).  So change that first.  Use a = different=20 brand to eliminate faulty batch manufacture. 
 
I once had a mysterious problem with an = RX4. =20 Chased it for weeks.  Turned out to be a bee in the fuel line. (I'm = serious=20 - the guy who owned the car used to work for me and is still around and = will=20 verify this!!).  Anyway,  Jack's pride & joy would work = just fine=20 around town.  But out on the open road,  it would run out of = fuel in=20 3rd gear (usually when overtaking).  Turned out that a bee (very = dead at=20 this stage) had got into the fuel tank. (The problem occurred = soon=20 after Jack filled up at some outback petrol station when he was on=20 holidays).  The bee immediately got stuck in the fuel supply=20 line.  At normal cruising flow rates,  there was sufficient = fuel to=20 run the car. On hard acceleration,  the bee's wings &=20 body would PARTIALLY block the supply line in the tank.  We = only found=20 it when we removed the tank,  replaced it with another one,  = and cut=20 the old one open.  You just wouldn't read about it in Ripley's or = the War=20 Cry!
 
I've also had pieces of fuel gum (and = one instance=20 a piece of cardboard) block the fuel pick-up.  When fuel sits a = long time=20 at a bowser storage tank,  especially if there is water at the = bottom=20 of the tank,  it will form a sheet of gum at the fuel/water=20 interface,  almost like condom latex,  (but nowhere near as=20 strong).  This film of gum gets broken up the next time a = tanker does=20 a dump,  and bits of this will very effectively block a fuel = pick-up, =20 or cripple a fuel filter. 
 
I've seen it happen on several = occasions over the=20 years.  It was particularly prevalent in the early '70s during = the=20 phase out of "standard" petrol before the introduction of unleaded into = this=20 country (all rotaries used to run on standard not super - which was = heavily=20 leaded back then).  I found out the hard way soon after I had = purchsed my=20 RX2 Coupe in 1971. Filled up at an "out of the way" petrol station = (where the=20 fuel sales volume on standard was virtually nil),  and immediately = had=20 problems.  After eventually getting back to Sydney,  we = quickly=20 diagnosed it as a tank problem.  Even steam cleaning the tank = didn't fix=20 it.  The tank was replaced,  and we cut open the old = one,  and=20 there was all these bits of gum,  just like a thin membrane tyhat = had been=20 cut up.
 
So the place I'd be looking is in your = fuel SUPPLY=20 system,  as it seems you have done everything else except check = fuel FLOW=20 rate.  Can't guarantee that this IS the problem,  but the = quick and=20 easy way would be to check your open flow rate at the carb,  and = then=20 compare it with somebody else's.  Alternatively,  you can work = backwards as you know that the engine requires at least 0.55 Lbs = per hour=20 per BHP at WOT. (First convert that to litres or pints or quarts = per minute=20 and you can direct measure it,  or run the fuel into a can for 1 = minute and=20 then go and weigh it).  Fuel flow rate should be at least 25% more = than the=20 max required at WOT so that your carb doesn't run dry.
 
One other area of the problem could be = the=20 incorrect needle/seat arrangement on the carb,  or a partially = blocked=20 filter at the banjo - I'm not privvy to what carb you are running = so this=20 is conjectural as I plead total ignorance of Lycoming carbs. =20 However,  all stock Mazda carbs have fine brass gauze mesh=20 filters,  both at the banjo,  and on top of the needle&=20 seats.
 
Additionally, in the racing 13Bs,  = an IDA=20 Weber would run out of fuel as the float bowl was just way too small for = anything over 250 BHP.  We used to replace the 2.5 needle/seat = assys with=20 3.0 units.  But  we would STILL run out of fuel on long=20 straights.  Extended float bowls were then added,  which = did fix=20 the problem,  but welding the Weber material was tricky,  = especially=20 if it had been saturated with oil laced fuel for a long time (sometimes = the=20 castings were slightly porous)..
 
My final solution was to add = an EXTRA float=20 bowl (from an SU carb),  with it's own needle & seat,  and = a fuel=20 return.   We could then go back to a 2.5 Weber needle &=20 seat,  as the 3.0 one was prone to flooding at idle and on the=20 over-run. (Nothing good has ever come of fuel dilition of engine = oil in a=20 race engine). This fixed all fuel flow issues.  Some time=20 later, affordable aftermarket EFI came along,  and all = this=20 passed into history.  But fuel SUPPLY issues are even MORE critical = with=20 EFI.
 
So these are just a few areas where you = can=20 look.  Be systematic,  and start at the connection between the = carb=20 and the supply line.  You will then quickly eliminate either the = supply to=20 the carb,  or the carb needle & seat itself.  If the open = pipe=20 fuel flow is more than adequate,  then I'd be looking inside the = carb for=20 restrictions.  As I have said,  this is only a guide.  = Feel free=20 to contact me off line if you feel the need.
 
Cheers,
 
Leon
 
 
----- Original Message -----
From:=20 kevin = lane=20
Sent: Sunday, July 24, 2005 = 6:33 AM
Subject: [FlyRotary] Lycoming = debugging=20 test - -HELP!

I realize that this isn't = exactly the=20 right forum, but you guys seem to have excellent debugging = skills.  my=20 local RV group is totally worthless ("I find the carnauba wax doesn't = show=20 fingerprints as much as the....")(except Mike!)  the on-field = mechanics=20 are sick of me coming by.
    my O-320 = RV-6A is=20 having RAG (rpm attention getter) problems.  it runs fine until = about=20 300' on take-off, then the rpm's drop to like 1700 (from 2200). =20 switching mags to electronic ignition(Rose) makes no difference.  = mixture=20 no diff.  pulling the throttle it will seem to run fine at=20 1700rpm.  I have 4 new cyls that I am attempting to break = in. =20 ground run ups can only go like 2 minutes before CHT's exceed 400=20 degrees.  I discovered I can get the rpm drop on the ground if I = run it a=20 minute or so full power.  cht's will typically approach 415 = degrees when=20 the drop takes place.  I don't know if the temp is significant or = not, it=20 does seem that way.  I have a brand new slick left mag.  = rose=20 checked the electronic ignition and could find nothing wrong, even put = it in=20 an oven to test.  I installed a new carb since the old one showed = signs=20 of leakage (and I'm at whits end).  no change.  my fuel = pressure has=20 been showing 8psi this last year, up from 6 psi when originally = installed.(no=20 idea why)  I installed a pressure regulator in-line which works = like a=20 charm.  I can dial whatever pressure I like.  2 psi makes no = difference.  I bypassed the mechanical fuel pump and ran it just = on the=20 facet electric.  2 psi, no difference. I discovered that you = can run=20 the carb for maybe 30 secs with no fuel pressure while it burns off = the bowl=20 gas. premier engines suggested induction leak making the engine run=20 lean.  no leaks detected cold or hot engine. (pressurized intake = with=20 vacuum, sprayed soapy water)
    if the = engine didn't=20 run right to start with then many explanations would hold.  but = it runs=20 fine for several minutes.  it runs the same under mag or = electronic=20 ignition both before and after the problem kicks in.  everyone = really=20 wants to blame the rose ignition, but I'm not seeing any = connection. =20 with such a quick run-up my oil temp barely registers, so I doubt = parts are=20 seizing.  I have new mineral oil in it for breakin right = now.  there=20 is a bit of MMO in the fuel too I believe, left over from a mechanics = "what=20 the hell" attempt from way back.  my cyls are all new, rebuilts, = so no=20 valve problems.  I checked the push rod lengths when I = reinstalled=20 them.  the engine isn't missing when the problems occurs, it = simply won't=20 run faster and it seems to prefer the throttle pulled back to match = the rpm it=20 is putting out.  I can't figure out any more lean mixture = scenarios to=20 try.  the new carb runs just like the old one did.  I = recently=20 replaced the mag harness with a much newer, used one.  I tested = it and it=20 was fine.  the plugs are all new, but again, no diff between mag = and elec=20 ignition.  if I flip the ignition to R and shut off the elect ig = then the=20 engine quits as would be expected, no wiring problems.
    fuel, = spark, air,=20 timing, that's all there is.  this damn lycoming lawn mower has = me=20 stumped.  my engine has been running fine up until this (hey, we = all have=20 "cracked" cylinders, get out your microscope and look!).  you = guys have=20 any ideas?
Kevin Lane  Portland, OR
e-mail-> n3773@comcast.net
----- Original=20
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