Author Topic: Engine goes rich after launch (Read 3258 times)

Mark Scarborough · « **on:** May 25, 2009, 03:01:22 PM »

Ok, After the regionals have ended, and I made my trek back home. I have a quandry! Pat and I spent the part of thursday night, and fridayworking on my Oriental. First the setup,,
Oreintal, 44 oz, it is from an ARC . I silkspanned and doped it, then finished with auto color and clear. There are pictures elsewhere. The powerplant is exactly the same as I flew in last years oriental which also weighed 44 oz.
Engine is an LA 46 with a .275 venturi and a Randy Smith needle valve. Tank is Uniflow and built up. It does run a fuel filter, and it does use muffler pressure. The muffler is a Randy S CNC tube muffler , which I totally love, great sound great look and works well. Fuel is GMA Powermaster 10 - 22 ( 50 50 castor synth) Prop is a wood version of the APC 12.25 x 3.75.
Now preface this all to say, the entire power train, from prop to tank is the same parts that flew all last year in my other oriental. as in the EXACT parts, NOT the same as,,,

so what happens is , I start it up,, set the needle to the always standard 9800 rpm on the ground. release it, sounds great for 2 to 4 laps then goes dead rich as in dropping to mid 6 second laps. I did have some flights with different props that only dropped to high 5 sec laps. Fuel is being consumed faster than normal, (not leaking out) Then my usual 2 or 3 lap lean signal at the end of the flight is now about 10 lean laps. I tried radically different props , theory initially was that it was cold, and the engine wasnt loaded enough. We tried everything from a 11 4, to a 12x 5. On one prop we did get the engine to hold speed fairly well . that flight launched at 10,200 rpm and dropped back into something that allowed me to fly part of the pattern.
The only difference essentially is that this engine uses a Plastic spinner, the other plane used an aluminum one, same size though. And this airplane has the standard Brodak ARC mounts hanging from the firewall instead of a crutch like my last one had.

Now My theory is,, perhaps this airframe on the ground has a resonance somewhere that is foaming or restricting the fuel flow, causing a false lean setting on the ground and that resonance changes in flight allowing the fuel to flow in a normal manner.
I open this to discussion.
My experience leads me down the path of correcting all kinds of lean conditions, but not many that I can think of that make a motor go rich, at least not this rich.
excepting one flight, it did not matter what RPM I launched at, it dropped back to essentially the same setting in flight. I even launched at 10,800, a full thousand rpm over normal, and it did the same thing, back to over 6 second laps.

so ,,, let talk!

Mark Scarborough · « **Reply #1 on:** May 25, 2009, 04:54:26 PM »

Been there, tried different fuel, even though that fuel was fine in my other engine, changed glow plugs,
could also be that this is the airplane that my girldfriend didnt want me to fly,, maybe she hexed it?

Steve Helmick · « **Reply #2 on:** May 25, 2009, 08:41:41 PM »

I assume that the old Ornamental with the short nose, long tail and wing mounted LG went to Stunter Heaven? Could any of the re-cycled hardware have some sort of damage? Can't see that a bent crank, backplate leak or tank leak would do that, but who knows?! Also can't see vibration causing this problem, but do you have aluminum pads under the engine lugs?

This Oriental, having the ARF/ARC cowling, I wonder if the aero of the cowl insides might do something weird to the air going into the venturi? Did you try it without the cowl? I would suggest trying that. Beyond that, I've got no ideas, so it's probably caused by the hex by a certain PHS Graduate!

Steve

Mark Scarborough · « **Reply #3 on:** May 25, 2009, 11:04:50 PM »

Steve,
thanks, yeah its the gear from that one, all the stuff was verified for suitability before the transplant. checked the crank runout, tank leaks and such.and as you said, most all the problems you see from that would result in a lean condition. I need to do an atopsy tomorrow and see if I can find any trace evidence. No metal pads under motor, wouldnt work with the cowl. The venturi extends beyond the cowl surface, just as it did on the last years version.

Strangly enough, when I called her to tell her that I withdrew from classis she didnt seem all that surprised, so I wonder,, hmmmmm

Steve Helmick · « **Reply #4 on:** May 26, 2009, 07:39:12 PM »

Ah. She put Birdshot in the fuel tank. That'll do it every time. Those small town girls do have some savy about dealing with the men in their lives.

Steve

Jim Oliver · « **Reply #5 on:** May 26, 2009, 08:56:12 PM »

Mark,
How is the tank installed/restrained inside the fuse?

On my Oriental arf, I smeared some RTV on the top surface of the tank and stuck it to the bottom of the balsa filler that is between the "exotic aisian hardwood" engine mount beams, then used some styrofoam to wedge between the bottom of the tank and the removable bottom block.

Has worked fine with a B40.........

Jim

Alan Hahn · « **Reply #6 on:** May 27, 2009, 10:15:10 AM »

Mark,
So does this remind you why flying electric is so easy??

Mark Scarborough · « **Reply #7 on:** May 27, 2009, 10:55:28 AM »

Alan,

I have no official comment at this time

but yeah it does! ( dont tell people its easy, they will say we are cheating!)

Alan Hahn · « **Reply #8 on:** May 27, 2009, 11:27:46 AM »

Quote from: Mark Scarborough on May 27, 2009, 10:55:28 AM

Alan,

I have no official comment at this time

but yeah it does! ( dont tell people its easy, they will say we are cheating!)

We are cheating!

RandySmith · « **Reply #9 on:** May 27, 2009, 11:48:55 AM »

Quote from: Mark Scarborough on May 25, 2009, 03:01:22 PM

Ok, After the regionals have ended, and I made my trek back home. I have a quandry! Pat and I spent the part of thursday night, and fridayworking on my Oriental. First the setup,,
Oreintal, 44 oz, it is from an ARC . I silkspanned and doped it, then finished with auto color and clear. There are pictures elsewhere. The powerplant is exactly the same as I flew in last years oriental which also weighed 44 oz.
Engine is an LA 46 with a .275 venturi and a Randy Smith needle valve. Tank is Uniflow and built up. It does run a fuel filter, and it does use muffler pressure. The muffler is a Randy S CNC tube muffler , which I totally love, great sound great look and works well. Fuel is GMA Powermaster 10 - 22 ( 50 50 castor synth) Prop is a wood version of the APC 12.25 x 3.75.
Now preface this all to say, the entire power train, from prop to tank is the same parts that flew all last year in my other oriental. as in the EXACT parts, NOT the same as,,,

so what happens is , I start it up,, set the needle to the always standard 9800 rpm on the ground. release it, sounds great for 2 to 4 laps then goes dead rich as in dropping to mid 6 second laps. I did have some flights with different props that only dropped to high 5 sec laps. Fuel is being consumed faster than normal, (not leaking out) Then my usual 2 or 3 lap lean signal at the end of the flight is now about 10 lean laps. I tried radically different props , theory initially was that it was cold, and the engine wasnt loaded enough. We tried everything from a 11 4, to a 12x 5. On one prop we did get the engine to hold speed fairly well . that flight launched at 10,200 rpm and dropped back into something that allowed me to fly part of the pattern.
The only difference essentially is that this engine uses a Plastic spinner, the other plane used an aluminum one, same size though. And this airplane has the standard Brodak ARC mounts hanging from the firewall instead of a crutch like my last one had.

Now My theory is,, perhaps this airframe on the ground has a resonance somewhere that is foaming or restricting the fuel flow, causing a false lean setting on the ground and that resonance changes in flight allowing the fuel to flow in a normal manner.
I open this to discussion.
My experience leads me down the path of correcting all kinds of lean conditions, but not many that I can think of that make a motor go rich, at least not this rich.
excepting one flight, it did not matter what RPM I launched at, it dropped back to essentially the same setting in flight. I even launched at 10,800, a full thousand rpm over normal, and it did the same thing, back to over 6 second laps.

so ,,, let talk!

Hi Mark

Sounds like a tank issue, if everything else is good. Check to make sure the tank or filter or fuel line is not touching or extremely close to the motor or muffler

Randy

Dennis Adamisin · « **Reply #10 on:** May 27, 2009, 12:04:14 PM »

Quote from: Alan Hahn on May 27, 2009, 11:27:46 AM

We are cheating!

Alan is right, to which I would add: "If you're not CHEETIN, then you're not TRYIN".

Mark:
From a purely pragmatic sense, ground/tach RPM means as much to IC as "static current" means to electric. If its too rich in the air at 9800, and rich but barely flyable at 10,200 then set the durned thing to 10,500 (or more or less) until the setting is one you can FLY!

So why is everything different bird to bird? Differences in AOL on ground (i.e shorter tail wheel) coupled with tank longer and or farther back. Flow to intake slightly different, spending TOO MUCH TIME (heat) on the ground setting the needle (hint, your goal is 10 seconds or LESS)

What about the "optics" of the prop - what is the tach seeing? Versus what it saw before on the other bird? Are the tach batteries the same as they were before? I have seen so much variance in tachs (even in the same tach) that it is a wonder that ANYONE can actually BELIEVE what the tach is saying.

Mark Scarborough · « **Reply #11 on:** May 27, 2009, 12:28:26 PM »

Randy,
thanks I will check the fuel routing. Would this fall under my theory aproach of a vibration induced condition that changes in the air? I do know the routing is confined somewhat.

Dennis,
To true on the tach setting, its a guide, reference. My other LA setup in a profile has to launch at 9600 because it leans as it becomes airborne, (profile Gee Bee) . My use of the tach is a "check point" as I listen to the sound of the engine too and the tach is agreeing to what I hear. The biggest thing is that despite what I set the needle for from 9800 to 10500 or higher, it dropped to virtually the same in flight setting which is NOT typical of any of my other setups that are plumbed the same way,, well despite one small niggle that now has me wondering. When I built this ship originally before i even started flying, I set it up with the needle coming out the opposite side of the nose, away from the muffler. This routes the "crap trap" filter behind the motor across the firewall. I think my cowling may end up with another hole in it. I am going to turn the needle around so the routing avoids putting the filter across the firewall, and into the more conventional position with the needle on the muffler side.

Randy Powell · « **Reply #12 on:** May 27, 2009, 02:42:40 PM »

Mark,

Well, Randy is probably right. In any case, you are getting more fuel than air soon after take off. My tendency would be to ground run it for 20-30 seconds to make sure the engine is up to temp, then set the needle with the tach and see if it still does it. If it does, you've eliminated the possibliy that the engine is taking time to come up to temp.

If the problem persists, then it's got to be some sort of air restriction that's causing it to go rich. Could be tank or fuel line or maybe crap in the NVA or a chunk of solder or something. Start changing parts out. I'd start with the tank. If it persists after changine tank, fuel line, filter and NVA, then you have to start thinking about engine damage that escaped inspection.

Mark Scarborough · « **Reply #13 on:** May 27, 2009, 03:19:24 PM »

Thanks Randy II
Pat and I ran it on the ground, thinking heat/cooling was the issue since it was rather low ambient temp. We even went so far as to run it into a lean two stroke for 30 to 45 seconds before setting needle with the same results.
I think tonight I am going to gut it, check the tank, and put all new fuel line in. may even rotate the needle assembly from right to left to straighten out the fuel line routing.
do you think there is a chance that if the needle outlet port was off, say pointing forward or backward, it would create this problem. I just rememberd Pat didnt like my needle saying it was to "loose" He is used to the stock tigre needle assemblies I think, and so he tightened the collet down, perhaps he rotated the entire assembly in the venturi bore?

Steve Helmick · « **Reply #14 on:** May 27, 2009, 07:46:30 PM »

That crosswise fuel filter has me bugged more than the NV being on the outboard side (fuel feed hose being on the inboard side). I wouldn't do either, tho. I'd like to see you delete the filter for a few flights, just to see if that is the source of the trouble. Then, change the spraybar to put the NV on the inboard side. One of these is going to fix it, I betcha...

Steve

Mark Scarborough · « **Reply #15 on:** May 27, 2009, 08:10:28 PM »

Steve,
explain your reasoning on removing the fuel filter please. I cant see where a fuel filter could ever make it go rich after take off? as for the needle, yeah its on the horizon. In fact I am stripping it tonight to investigate. I finally faced reality and the Avenger wont be ready for Puyallup regardless so I need the Oriental to be airworthy, and more so trustworthey!
I do NOT like to run my motors without a filter. If I swap the needle around, I will have an extra hole in the cowl, small price to pay if it fixes the problem. but loosing the filter,, I have bad feelings, and experiences not running a filter. As in they only clog the needle on an official flight, never in practice!

Larrys4227 · « **Reply #16 on:** May 28, 2009, 05:19:33 AM »

I am by no means an expert in this area, but thought I'd offer an experience. Evo36 on a profile with a standard vent 4oz tank and filter.... runs good with the exception of slight speed up half way through the flight. Been reading alot about unilfow tanks and thought I would try one from eric to stabilize the whole flight. Uniflow tank is same capacity and dimensions ... a direct swap out.

For 12-15 test flights, I had the exact problem as described here. Good tach on the ground, launch, and within 1-2 laps the engine would go horribly rich. Tried all sorts of things ... pressure/no pressure on each vent, filter/no filter, shimming rear of tank, tank height, NV adjust leaner at launch, .... nothing changed it going rich 1-2 laps in.

Got frustrated and gave up .... re-installing the standard vent tank. It went right back to running perfectly, with the exception of the speedup halfway through the tank. I can live with it ....

I'm watching this thread with great interest .... please post if you find your fix!

FlySafe! Larry (Larrys4227)

Leo Mehl · « **Reply #17 on:** May 28, 2009, 09:13:05 AM »

I defently think it is a tank problem. I have used old tanks that ran fine on the original plane but in reuse it did not work at all. Make sure needle valve hole is pointing strit down the venturie and replace tank. If this was used after a chrash the tubes sometmes are not uin the same place they were before. Take tank end ouoff and check to make sure that tubes are still where they should be. If they are not put in new tubes.

OR check girlfriends pockets.

Randy Powell · « **Reply #18 on:** May 28, 2009, 11:03:04 AM »

I actually point the hole in the NVA toward the block, about half way between straight down and 90°. The probably is probably the tank. That has the highest liklihood. Second would be fuel lines, crimps that happen after take off or some such. I don't think the inlet being inboard or outboard makes any difference at all. I've done it both ways without issue. Heck, my current profile has the engine mounted at about 75° canted and the needle sticks up toward the inboard side. Makes it sort of an outboard pickup. Kinda. Engine runs great.

Alan Hahn · « **Reply #19 on:** May 28, 2009, 03:58:40 PM »

Here's a guess.

It sounds like the tank is plumbed "normally", e.g. not uniflow. So on takeoff the engine will go rich.

Do you have the overflow/uniflow vents hooked up correctly (not reversed)

Maybe the shock treatments you have been getting from the E-Power have affected your memory!

Mark Scarborough · « **Reply #20 on:** May 28, 2009, 04:34:52 PM »

It is a tank I built, and it is Uniflow. for it to go rich from the tank, it requires that either the tank have reduced pressure on the ground, or by inverse, increased pressure in the air. I just dont see where it could be getting that unless its a foaming on the ground issue,,
yes perhaps I long for electroshock therapy,,, flip the switch and fly right Alan?

EddyR · « **Reply #21 on:** May 28, 2009, 07:09:02 PM »

I had this same problem on my Cobra many years ago. I changed everything and still had the problem. I found that the filler tube that also served as the uniflow vent was part way blocked. I replaced it and then found the blockage.
Ed

Mark Scarborough · « **Reply #22 on:** May 28, 2009, 07:15:06 PM »

Intyeresting,
I will certainly check that. I am thinking about building a new tank, but I will check that first, maybe even pull tha back off my tank and look. The thing I dont get is the dynamics of what is causing it.

Mark Scarborough · « **Reply #23 on:** May 28, 2009, 08:12:53 PM »

Well Ty,
come on over, your welcome to the air mattress , the couch, the floor, its all there, the cat may share with you though for some reason he has an affinity for the air mattress!
same venturi, same fuel, same muffler, same tank, same proximity , tank to motor, same fuel filter same prop. something changed though, the rigidity of the nose I know is not as good,, which is what leads me to think about a vibration on the ground that goes away in the air. I did note that the needle was out over 4 and a half turns,, ( its a randy needle) which is over a turn and a half from what this setup normally runs at. I am going to look more closely at the tank.
OBTW, Pat and I have probably 6 or 7 hours of steady work trying to sort it out at the field in Eugene.. sigh,,

Steve Helmick · « **Reply #24 on:** May 28, 2009, 10:00:55 PM »

"I'd like to see you delete the filter for a few flights, just to see if that is the source of the trouble."

Mark...Above is what I wrote previously. "For a few flights" won't be a problem...maybe you'll need to hose out the spraybar when you put one back in, but probably not. What did we do back before fuel filters were available? We were careful with our fueling and we cleaned the spraybar more often.

I'm just wondering if the East/West alignment of the filter might have an effect, or the NV being on the outboard side of the engine. Try it without the E/W filter first, see if it changes. Then change the spraybar and put a filter back in. I still have that tiny RO-Jett filter, and you're welcome to it. Remind me at Stunt at Thun.

The RO-Jett filter was in Eugene, of course, and my pocket knife woulda made a hole in the other side of your cowl... Since you're home, take the spraybar out, remount the cowl, and drill through the current hole and engine, to put the hole in the right place with a 5/32" drill.

Steve

Mark Scarborough · « **Reply #25 on:** May 28, 2009, 10:13:32 PM »

Done, done , done and done,,
I pulled the engine, replaced the JIS screws with allen head cap screws, rotated the spraybar, all new fuel line, and fuel filter oriented in a semi normal manner, pulled the back off the tank and ran a wire through all the tubing in the tank, then resoldered it leack checking it of course. I have a spare engine to bring, I am also plumbing a clunk tank for backup to try incase,,,,,, checked the pressure fitting on the muffler and inside the muffler. I think I am prepared,, well as well as I can be. I hate not having confidence that I found something amiss,, guess the only way is to try it, then if problem persists, swap the tank, then swap the motor. I also cut the needle valve stem off shorter in case there was some funky vibration thing happening there.
keep your fingers crossed, sure wish I knew if someone was flying Sunday

Greg L Bahrman · « **Reply #26 on:** September 01, 2009, 08:16:55 PM »

Mark,
Did we ever get this straightened out

Steve Helmick · « **Reply #27 on:** September 01, 2009, 10:21:05 PM »

I think some electrons contaminated his Powermaster 10-22, and then the GF made him hang it back on the livingroom wall. I heard a mention of lawyers, too. That not good, Kemosabe! I haven't seen Mark at a contest since Memorial Day (NW Regionals). Very unusual! I hope he can drag himself and his flying buddyette over to the Stevenson/Roundup, September 12/13. Patrick, too...bring your flying buddyette!

Steve

Mark Scarborough · « **Reply #28 on:** September 02, 2009, 12:35:01 AM »

I did actually get the engine run corrected, alas, the trim problem was never overcome, nor would it be. There were some internal issues regarding the control system that I deemed innapropriate to resolve. Since this is my GF fav airplane, and if I had stuffed it, it was decided that it is now permanent wall art. In fact, I made her cut the leadouts just so she would know its hers.
Steve, I was in Puyallup. I only have my Gee Bee ready to fly, and some other issues at home have cropped up. I wont make Chehalis sadly,, still hoping for The Fall Follies,, just have to wait and see,,,,,,, Pat, Randy and I are all in kind of the same boat right now,, we are gathering forces for next year when we plan to dominate the stunt scene with previously unseen levels of fun,,

sure miss you guys though,,

Dennis Moritz · « **Reply #29 on:** September 04, 2009, 06:59:43 AM »

What fixed the engine run?

Mark Scarborough · « **Reply #30 on:** September 04, 2009, 04:27:37 PM »

I really am not sure to be honest. I basically gutted the nose and started over, I checked the tank for leaks, there were none, I desoldered the back of the tank and checked the lines inside, all good, I ran new fuel line, cleaned needle, checked tightness of all fasteners on the engine and found nothing amiss. I reassembled it all with the only reused componant in the fuel system being the filter,,

and it ran fine. To bad there was control system issues. I used the supplied hardware including the pushrod from flap to tail that came with it. That was a msitake. I elected not to cut into it to fix it and instead its now wall art.