Posts: 1791
Joined: 7/5/2005 From: Port Orchard WA, USA Status: offline
What is the spacing between your cowl and the carb opening? That's the only thing I can think of that would effect it. You should have 1"-1.5". If it's too close it will restrict the air flow and cause it to run rich. Apart from that, you're on your own cos I wouldn't have a clue either. I ran mine yesterday just to get some gas through it and it's turning 6550 with a Vess 22A which really loads the engine. It's in a WH Edge 540T V2 so the cowl is well away from the carb. I also ran my metering line into the fuse and a pill bottle to keep it away from swirling air and pressure differentials.
< Message edited by Lou55 -- 9/1/2007 4:26:07 PM >
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Take Offs are Optional, Landings are Really Nerve Racking!! Al Lewis AMA #821623
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Joined: 2/25/2002 From: Central, CA, USA Status: online
If the carb throat is too close to the cowl it creates a venturi that changes air pressure considerably on the diaphragm. This issue is not by any means limited to a 3mm engine, but is quite common to most of the high performance engines used inside a round cowl aircraft. It's been driving people nuts for about a year and a half now, and has at least one engine manufacturer developing a new carb to over come the issue.
You have to block the airflow around the diaphragm or redirect the pressure intake to the diaphragm. It's all trial and error.
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If you can''''t fix it with a hammer, you have an electrical problem.
I take back what I wrote, I thought we were talking about the Evolution 58. IF this is the 3mm 53, of course I will try to help.
I agree that the carb entry must be clear, if it's near the surface of the cowl that will create a restriction with the cowl on. Check that first, if you don't get it figured out give me a call.
I can't believe I said I have no ideas, it was early in the morning. Sorry.
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Joined: 1/9/2002 From: stevens point,
WI, USA Status: offline
quote:
ORIGINAL: rctom
The initial timing should be set at 28 degrees. This ignition works like a C&H to retard the timing at low speeds, so initial is set at total.
TF
Tom, when the crank is turned (with a degree wheel) it sparks at 20 deg before TDC. There is not enough adjustment to change it to 28 deg before. So let me get this straight. Turned slowly as described, it should spark at 28 deg before TDC right?
John
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If we all think and say the same things, only one of us is necesary.
Tom its all good. I spent the day at the field today with all my WildHare planes. First off the Honda we tached her again with the same tach and it turned a respectable 6700rpm with a 22 X 8 MSC. I am sure It is still a bit rich. When i pick it up off the bench she loads up. Once air born and inverted it richens up. My guess is the air pressure inside the cowelling is causing this. I also noticed when I do a wall and snap the nose up she studers a bit. Next time out I will try a few things and run it without the cowelling to observe the performance.
The Evolution 58 with a Vess 24A Turned 6700rpm as well that I have in the Cap-232-85" Ran a lot better today I added a baffel to the coweling to increase air flow over the engine. This was a marked improvment. 3-D performance was flawless However after a long run and a few touch and goes It would still sag a bit if you punched it up from a dead slow idle. On this one Im going to open up the exit whole a tad more and burn more fuel Im sure she will come around.
The DA-50R in the ultimate with a 23 x 8 MSC turned 6500 and as per ussual Rock solid
Tom sorry if I confused you I do have a few of these things kicking around.
Tom, when the crank is turned (with a degree wheel) it sparks at 20 deg before TDC. There is not enough adjustment to change it to 28 deg before. So let me get this straight. Turned slowly as described, it should spark at 28 deg before TDC right?
John
Yes that's correct, 28 degrees. Contact me directly about this.
Tom its all good. I spent the day at the field today with all my WildHare planes. First off the Honda we tached her again with the same tach and it turned a respectable 6700rpm with a 22 X 8 MSC. I am sure It is still a bit rich. When i pick it up off the bench she loads up. Once air born and inverted it richens up. My guess is the air pressure inside the cowelling is causing this. I also noticed when I do a wall and snap the nose up she studers a bit. Next time out I will try a few things and run it without the cowelling to observe the performance.
Dan:
Call me about this, there is a fix for the cowl-pressure thing. 817-430-0107.
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Joined: 8/25/2002 From: FPO,
AE, USA Status: offline
quote:
ORIGINAL: rctom
quote:
ORIGINAL: bluemagic98
Tom its all good. I spent the day at the field today with all my WildHare planes. First off the Honda we tached her again with the same tach and it turned a respectable 6700rpm with a 22 X 8 MSC. I am sure It is still a bit rich. When i pick it up off the bench she loads up. Once air born and inverted it richens up. My guess is the air pressure inside the cowelling is causing this. I also noticed when I do a wall and snap the nose up she studers a bit. Next time out I will try a few things and run it without the cowelling to observe the performance.
Dan:
Call me about this, there is a fix for the cowl-pressure thing. 817-430-0107.
TF
I too would like the fix. Do I have to call from Japan to get it?
Here's what I did on theone I had that was giving me trouble. It would run fine upright and at full throttle, but when in knife edge and inverted at partial throttle it had a tendency to go rich and blubber, returning to normal flight made everything go back to normal. THIS IS NOT NECESSARY ON MOST ENGINES, we've only seen it in a few cases.
I did two things to correct it. The first is to rotate the reed block/carb assembly 180 degrees. THis alone will probably correct it, after you do this the engine will be running way too rich, it will be necessary to lean the hi end to get max power.
The second thing was to route the enrichment-diaphragm cover vent around to the entry of the carburetor. This will lessen/eliminate any problems from fluctuating cowl pressure. To do this;
1 remove the cover plate and drill the vent hole to 1/8". Using JB weld glue in a piece of 1/8" brass tube about 1/2" long. Reinstall the cover plate and attach a piece of tygon tube to the brass tube.
Make a small bracket outof brass sheet with a 3/16" hole in it, and solder a 1/2" long piece of brass tube to that bracket so that bracket then can be bolted down to one of the carb mounting bolts so that the vent is immediately above the carb entry. Connect the other end of the tygo here.
It sounds complicated but it only takes a few minutes. I still do not fully understand what is going on, but I and other distributors have asked the manufacturer to switch to a V-type reed block which should eliminate the directional nature of the reeds which seems to be causing the problem in a few cases.
Photo attached.
TF
< Message edited by rctom -- 9/2/2007 5:13:33 PM >
Posts: 649
Joined: 6/11/2004 From: Ofallon,
MO, USA Status: offline
Hey Tom, I have one of the first batch of the 53's you sold, and the trouble I am having is when I roll from level flight to knife edge it burbles and hesitates briefly but then comes right back to running normal while still in knife edge. Also when I am doing knife edge snaps it does the same thing, but when doing upright snaps it does not seem to do it as much. do you think the mods you mentioned will work for me? or should I leave well enough alone as the problem is not that bad.
Posts: 1791
Joined: 7/5/2005 From: Port Orchard WA, USA Status: offline
This is a standard modification done to all gassers as far as I know. At different attitudes the metering plate will experience different pressures causing it to deliver different fuel amounts. I simply thread the hole for a 8-32 and screw in a pressure nipple from a muffler. Once tight I turn it over and grind the excess off on the inside of the plate so it can't come in contact with the diaphram. I then run a 1/8" fuel line from there to the inside of the fuse and stick the end of the line into a hole in a pill bottle or film container. This ensures the pressure will remain constant at any attitude (POSITION, not HEIGHT) and the engine will run constant as if there were no air swirling around anywhere. Scott and Mike over at Billelli Engines do the mod I described to every carb prior to shipping the engine. Sorry, guys but I thought you all knew about this one.
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Take Offs are Optional, Landings are Really Nerve Racking!! Al Lewis AMA #821623
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RE: New 53cc engine now available - 
