AA5BY

If wishing to isolate the cowl from the fuselage interior, one way to do that is by using a hole saw for the carb cut out in the firewall and then inserting a solo cup, marking it and cutting it to length. IIRC a three inch hole saw was used.

AA5BY

There have been critics of the long mounting standoffs for the MLD-35 and I don't have any idea if the criticism is justified or market competition driven but given that there was one other issue at play, I decided to kill two birds with one stone.

I made an aluminum ring from 1/16 stock to mount between the standoffs. It might provide some vibration damping at the standoffs if such exist and it moves the motor 1/16" further from the firewall, just enough to eliminate the conflict between the firewall and getting access to the HS needle for adjustments.

If severe vibration exist, the light thin ring of course will stress crack. A thicker ring could be used but it might require longer bolts and add weight. The 1/16 thick ring weighs very little.

AA5BY

Steven.... in finishing up the final mounting of the MLD-35 on my current project, I noted that the throttle arm has play. The play is between the butterfly shaft and the arm. The shaft is shouldered and the arm fits into the shoulder and is keyed on two sides to prevent rotation. The problem is the keys do not eliminate all rotation and the screw which holds the arm on bottoms to the shaft before contacting the arm so it leaves the arm with some play on the keyways.

I added a washer with a hole just larger than the butterfly shaft so as to compress the throttle arm against the shoulders and stop the play. Do you think doing so will adequate check the arm looseness?

AA5BY

I fired up the MLD-35 today and think the ignition might be bad right out of the box.

It popped after just a few flips with choke on, choke off and it would burst a few rpms after a few flips. This cycle was repeated perhaps a half dozen times. The low needle was opened a slight bit and it came to life. It will idle fine, but misses at midrange and will not achieve any top end and the elevators are suffering RFI.

I'm disappointing. I was careful to ensure that no battery was hooked to ignition until after plug cap was well seated over the hex part of plug.

Do I want to press Cermark for a replacement Melody ignition or just bite the bullet and get an RCXcel?

Jimeni

I would try a replacement first, can not hurt.

I use to have an mld 35, never even ran it. Only took it out of the box once to inspect it. I went to get it out of the closet to put in place of the 28 on my extra, and its gone. And of course no one touched it or knows where it is. It is no where to be found. We demolished the house and garage looking. It is gone.

91zulu

My Feedback: (2)

Did you check the plug cap. Word is there may be a loose connection in there with the resistor wire not attached properly to the part that goes around the top of the spark plug that C looking clip. Also check the Hall sensor and ignition connection, the connectors . There may be a loose wire there too. Everyone should do these checks before going out to the field to be sure all is well.

AA5BY

It sure starts easy and runs smooth. I've finished a scratch build plane the engine is in except covering the wings so they were not mounted and that usually will allow quite a bit of shake of the stabilizer but there was very little.... I was surprised and pleased by the low and smooth idle.

Bummer on the lost engine. I've sworn at times something is gone... but usually find it later. Hope it turns up.

Thanks for the heads up about inspecting the cap. A look inside revealed the metal contact was recessed perhaps 1/8" deep within the silicone, which seems odd. I'll look at it closer tomorrow.

AA5BY

The cap might be the problem... or at least part of it. Using very long and slender needle nose pliers, I grasped the metal contact that was canted sideways and deep within the silicone and centered it and pulled it near the front edge of the hole in the silicone and ran the engine again with less missing and the ability to run up to full throttle. There is however still RFI influencing the elevator servos at anything above an idle.

I'm going to do surgery on the cap to insure that the ground braid is soldered well to the cap, that the contact is positioned where it can contact the plug and that otherwise all looks well.

Will report what is found.

AA5BY

The ground braid was well soldered to both sides of the cap. There was no resistor. There were no burn marks in the silicone or on inside of cap. I'm not going to mess with it further... ordering an RCexl.

Jimeni

I was getting RFI with my SPE 43. Turned out that the metal cap was vibrating very slightly. Put a zip tie around the base of the metal cap, and RFI was 100% gone.

AA5BY

I've been putting small hose clamps on all my gassers but hadn't done so on this as it wasn't buttoned up yet, but I'll try that. I've an RCxl ignition ordered and will talk to Cermark. It has a Champion Y 82 plug that is not a resistor plug and there is no resistor in the cap, though I have no understanding if that has any bearing.

I am very impressed otherwise with the ease of starting and smoothness of running. And... it did go to full power once long enough to get a tack reading of 8,000 with a Vess 18x8 though I've of course no ability to know if this is the best HS setting. It has a very smooth idle but continues to miss starting shortly after going above idle.

As to the RFI... I don't know yet what to think of it other than I don't think it is getting into the receiver (72mhz using PCM) as the throttle and rudder servos are rock steady but it drives the elevators full throw.

91zulu

My Feedback: (2)

Which RCexl did you get and from where? I`ll get one just in case things goes south on mine. Maybe post a link.

DaleD

http://www.agaperacingandhobby.com/v...php?groupid=39

Choose the ignition for your engine depanding on the type plug which fits your engine.

AA5BY

I ordered from Magnum RC simply because it came up in a search (price was the same), the CM-6 plug, which I think is the same plug as the Champion Y82 a 10mm plug that came in my MLD-35. The exact part number was BHCign10.

I did call Cermark and was told that the guy I needed to talk to was off to a show and to submit my problem in an email but I really don't want a replacement Melody ignition.

When Ralph (Antique) speaks... I listen and he outlined the early failure (second run IIRC) of the Melody ignition on his MLD-35 but otherwise had good things to say about the engine and claims it stronger than a DLE-30. My engine is in a self designed - scratch build plane that I'm a little emotionally invested in and at this point simply don't trust Melody, whereas I've had several RCexl ignitions without a single glitch... so have some degree of confidence in them.

I'll report to the forum after running the engine with the RCexl, whether the missing and RFI problems are solved.

91zulu

My Feedback: (2)

Great thanks.

AA5BY

The RCexl ignition came today. Installation was little problem. Remove the old hall effect transistor and test the new to determine which pole of the magnet makes it happy.... it needed flipping over. It was centered within the 1/8" adjustment and that was it. The engine fired up, suffered no missing, revved and held steady at 8260 (Vess 18x8) with carb not yet adjusted. And.... there was zero RF problems, though I've not yet done a range test.... at least there was none of the elevators going full over as was the case with the Melody ignition.

Rocketman_

Other sources,
http://www.rcextremepower.net/ignitions.html
Rcexl ignitions For Single cylinder with NGK CM6 plug $54.95
Plus free ignition tester $14.95 value

http://www.shop.kavarootusa.com/product.sc?productId=12
Rcexl ignitions For Single cylinder with NGK CM6 plug $53.95

AA5BY

My MLD-35 was run again Friday to dial the needles in. Running a Vess 18x8s it turned 8400 and was detuned to 8250-8300. Range check was normal.

Of note is that the idle is not as smooth as it was with the Melody ignition though I'm not necessarily saying that to be ignition related as I did have the prop off to change the ignition and the prop could have been remounted 180 degrees differently. The prop is balanced but it could favor one position. When removing the prop to reinstall the cowl, I flipped it again and will note any change. The shake was typical to what I see with most engines. However, the idle was unusually smooth with the Melody ignition.

There is only about 1/8" timing adjustment range when mounting the RCexl with the same screws as used for the Melody and I suppose the timing might be slightly different. I failed to rotate the Melody pick up to note how much adjustment it had.

pe reivers

I took the liberty of plotting power curves for the MLD35 against the data I have on MVVS35. Lacking open muffler data for MVVS, I took tuned pipe data. The curve looks a bit weird, because I have no data above 8300 rpm. MVVS has peak power at 9000 rpm, but is mostly operated in the 7500 rpm range. The MLD curve is dark blue.

AA5BY

From your graph... it looks like I should exchange the Vess 18x8 prop for another prop I've on hand an APC 19x8w, which according to the the numbers supplied will turn about 7800.

pe reivers

From this graph, I would not choose a prop that runs between 7,600 and 7,900 rpm (rising torque). Props in that range tend to cause engine sagging when getting hot. The jump in torque indicates some kind of muffler resonance. My prediction is based on history data. It's hard to tell how much truth of that remains in the resonance shift for the quite open Chinese mufflers.

captinjohn

I think someone should start a new thread. Know ignition curves& effect on engine behavior. All postings would be just related to that. Maybe we caould all benifit. Capt,n

GEORGE_32

this is my ignition ... i am from the first owners of mld35 i bought it from sdshobby and the package came with the old ignition that was square and not as this one in the photo (this is the new ignition that its supposed to have resistor..)
this is my story,.. package came from the shop ... and later i discoverd that the old square ignition was replaced in the next batch with that in the photo i asked for replace and it was replaced (the old one didnt had the resistor inside the cap so there was interference even in the 2,4 ghz rx jitter and problem in the servos from the shop they asked me if i wanted to send me the resistor and me change it or to send the ignition and to be replaced with new one... )
in the photo also you will see a coil (spring that is not included in the ignition but it was spare from the dle 20 and because the rcxl has it for the pipe i put it also .. )
so this ignition does not have resistor inside ??
the motor is strong and i think its has better behavior from dle (idle, response , and power )
if it create any trouble ..i am not going to risk it ./.. i will throw the ignition away ....and just put rcxl ...

AA5BY

The ignition that came with mine looks exactly like the one pictured. It did not have a resistor in the cap so I think that means that you can't assume yours does. Mine was shipped 5/12/11 or slightly less than a year ago. Unless your ignition is newer than that... I'd question whether it has a resistor.

The engine would start fine on the ignition and idle great but above idle would miss, fail to produce full rpm and produced RFI that drove the elevator servos hard over.

DaleD

Hello,