mihelone

Hi there.
I have a ZDZ 50 NG with 22*10 menz wooden prop.
I get 6100 rpm out of it (unleaded gas, 40:1 synth oil) but I think it should be better Sad Sad Sad
Anyone with any experience from this engine HuhHuh??/

juanes1969

I used to have one of these engines, it is a fine engine by all counts. However you need to take very good care for it when breaking inn. I used pennzoil at 32:1 for about 5 or 6 gallons. I sold before going to synthetic, but still fies in my club. It spins a mejzlik 22x8 at 7100 rpms and idles at 1500. It´s still on pennzoil.
I remember I tried a bambula 22x10 on this engine and the rpms droped a lot (about 6500) so I kept the 22x8. Some people here are getting between 6600 to 7100 on a variety of 23x8´s. Maybe your prop has something to do.
Some more info would help: How many fuel has been ran through it, what temperature is it reaching, type of muffler, etc that way you´ll get better help.

John

mihelone

Dear John,
thanks a lot for your reply.
I use a bcm wrap around pitts muffler. the engine has burned about 70-80 liters of gasoline mixed with 40:1 full synth oil, so it is fully run in. I think its a matter of prop size as I suppose from your writings...

Zeeb

My Feedback: (41)

Have you cut the crimped tips off your Bisson? That's supposed to add a chunk of RPM due to less restriction.

Have you verified your ignition timing?

Have you reset your needles as the engine broke in?

Where I live it's 4500' ASL and we have to run smaller props to get decent RPM out of the engines but even here, my 50NG with a 22x8 Mejzlik will spin at 7200 RPM measured with a TNC tach.

JoeAirPort

My Feedback: (41)

Certainly too much prop and maybe a restrictive exhaust. Probably both. I have two of these and LOVE them. I will not sell either one. They both do about 7000 on a MEnz or Xoar 22x8. That's the prop you should be running. 22x10 is too much. It's possible you also need to tune it better.

Panzlflyer

My Feedback: (15)

try a 23/8

mihelone

hi there.
the timing is perfect and the needles are where they should be after the running in. I think it's the prop size...

mihelone

maybe a 22*8, as you say, should give a proper rpm...

mihelone

hi there.
yesterday I went flying with my Great Planes Pitts Special 1/3 (the ZDZ is on its nose) and after 11 minutes of flying the engine flamed out at 50% of throttle stick position...fortunately the damage caused by the forced landing is not as big as expected...
any ideas on this out of cause flameout?
the tank was 50%full, the ignition pack voltage was ok and the fuel was 40:1 unleaded gas and synth oil (after an email to the zdz distributor I was assured that there is no problem to use unleaded gas )...[][][][][]

JoeAirPort

My Feedback: (41)

Maybe too much prop and it over heated? Neither of my ZDZ 50 NG's have flamed out.

altavillan

My Feedback: (1)

Need lots more info. ZDZ's nor any other engine don't just flame out without a reason. Common reasons are Ignition dieing, and 20 things can cause that to happen. Fuel quits flowing and 30 ways that can happen. Engine can over heat and there's more than a few causes of that.

JoeAirPort

My Feedback: (41)

Yep I have to agree with that. BUT he starts out the thread stating that he is over propping the engine and backing that up with a very low RPM for this engine....heat is one obvious answer.

And also when do you ever get that much information on the problem in these forums? Never. We have very little to go by. So anyway that's my answer based on the info provided.

altavillan

My Feedback: (1)

Wasn't attacking you Joe. No reason too, I did reply to mihe. And this one does also.
mihe, did your engine start easily, always? That would eliminate a bad fit on the timing disk. Pulse port blockage, fuel pump issues.
Did fuel remain in the line after shut down? Always?
Did the engine die suddenly? In level flight? If so it starved for fuel or the ignition died. Bad plug. Klunk stuck forward. etc.

Were you able to turn the engine over after the flame out? Does it still have compression? Did it smell or feel hot?
The diaphram and fork heigth provide the needed fuel reservoir for the engine to draw fuel through the needles. Have you removed the diaphram and inspected those parts? The reservoir meter, high and low needles, and timing all have to be right for good power to be made.
How much clearance does the carb intake have? Not backed up against the firewall?
Have you checked the timing? Ever adjusted it for best opperating location?
Many more questions if these don't seem to point to a cause..

mihelone

Dear altavillan thank you for your interest. I 'm going to answer all your questions.
the engine starts after 3-4 flicks. fuel remains in the line after shut down.
the engine died suddenly in level flight at 50% throttle.
it turned after the flameout and had the usual compression. the sensor and needles were set by the instructions and for best performance.
there is a fairly big cut out on the firewall for the carb intake which has a ZDZ venturi fitted.
I 'm going to start the engine today and give more info on its performance after the flame out.
thats all for now...

mihelone

good evening.
after some investigation I found out that the engine flamed out due to a bad ignition. the ignition system doesn't always produce a spark.
so I am going to fit a new Rcexl ignition. I 'll keep you informed...

mihelone

these are some photos of the PITTS before the flameout...

JoeAirPort

My Feedback: (41)

How's the ZDZ running with the new ignition?

mihelone

good morning.
I just fitted the new ignition yesterday. I used the zdz sensor, just cut the black cable and fitted a female plug. The sensor offered with the ignition does not have a proper plastic base to fit on the ZDZ, since the distance of the holes on the crankcase for the screws is too big. However it is suitable for DL and DA engines. The spark produced is very strong and bright, it cannot be compared to the one I had with the old falcon ignition, whenever it produced one.
I 'm going to run the engine this week, so I 'll give more info on the engine's performance...

mihelone

hi there
yesterday I flew the pitts with the new ignition. the engine starts as before and the throttling is the same.
What is different is that I get 5600 rpm at full power, 400 rpm less than before, with the same prop (22x10) and fuel mixture. what was different was the ambient temperature, 36 degrees celcious. thats all for now, I 'll come back with further test results...

mihelone

photo of the bird...and me in the backround...

uduman

This was posted on another forum, it might help you...

Has an interesting problem with my walbro carb on a ZDZ50NG, so I thought that I would post for your interest.

"Took a flight, everything was normal, but when I landed and went to taxi back to the flight line, the engine stalled. This never happended before. Although I thought nothing of it. Later, when I went to start up the engine flooded.
Pulled the plug three times and the plug was full of fuel. I gave up and packed it in for the day. Took the cowling off to find fuel coming out of the air inlet of the carb. Disassembly of the card proved to be a stuck metering valve. It was stuck open. Removed the assembly, cleaned and changed the valve and diaphram while I was at it. Works fine now."

Uduman

mihelone

hello there
I tested the zdz with a menz 22x8 and had 6100 rpm, 500 more than the 22x10.
I 'm thinking of changing the piston ring as a last resort to get more rpm , just a thought...

mihelone

Hi
I 've changed the piston ring and the gasket
the result: after 4 tanks for the piston to setle, 6100 rpm with the menz 22x8, so no gain from all this procedure.
the matter is that the engine is still hard to start or sometimes refuses to start at all.
anyone with the same problem?

JoeAirPort

My Feedback: (41)

Still about 700-900 RPM's too low. What exhaust are you using? Did you try to richen the high needle a lot? Maybe you are just to lean? I'd make sure you are on the rich side of the RPM peak. Then when you know that for sure, lean it to peak.

mihelone

thanks for your fast reply
the exhaust is a bcm pitts muffler. the high needle is set just a beat before the lean setting. if I lean it more then there is a prm drop.
if you see the prevous posts, I use a new ignition.
What makes me most unhappy is that the engine is unwilling to start and the a DL-50 I have works without loosing a bit, starts at second flick and costs 1/3 the money...