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Old 10-02-2019, 05:30 AM
RCdude13 is offline
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Took some pics of the engines going back together. The 97 RV crankcase is what they sent me and it works for my 90 crank, head, etc.
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Old 10-02-2019, 06:26 AM
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Cool,let us know how it works.
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Old 10-02-2019, 06:35 AM
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Weigh the odds: the number of engines with carbs pulling air from inside the fuse compared to the number of failures from "sucking in bolts". It seems a bit odd the amount of ZDZs failing from "debris" compared to every other engine.
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Old 10-02-2019, 01:20 PM
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more than likely a "failure" from within.


BV
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Old 10-02-2019, 05:13 PM
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It would be better if ZDZ just sold the engines as high performance engines with NO warranty.

O.S. has been doing this for decades with their r/c racing engines for the cars. People still buy them and they dominate. However, it is explained upfront that you are on your own.
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Old 10-02-2019, 06:59 PM
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The crankcase did not have a mark on it for setting the location of the sensor. I just measured it of off one of my old 90's. I fired up the first engine in my Hellcat. It ran well, had a ton of power, but eventually started stopping whenever I went to full throttle. If I backed off as soon as i noticed it starting to die I was able to keep it running. I was using a Falcon 26 x 10 prop. Any ideas?

All in all, I am pretty happy with the results.
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Old 10-02-2019, 08:57 PM
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ZDZ's never had any kind of timing marks on them so they published a quick way to set the timing or you could go to the degree wheel monkey business.

If the trigger, I've forgotten the real name, mounted in the hub is lined up with that casing rib on the exact side of the case, the piston is at TDC. Draw a line on the hub with a marking pen and backup the crank shaft a bit. Then draw another line on the hub at 6.5mm, 7.0mm distance from the first line. That works for the bigger engines, below the first line. Rotate the crank back to where the second line you drew, lines up with the casing rib, set the pickup so it is centered on the first line you drew and you're done.

Dick Hanson who used to be known as "Mr. ZDZ" here in the USA because he helped ZDZ develope the engines, used to say, "just slide the pickup all the way to the end of the screw mounting slots and tighten it down. Believe it or not, that surprisingly accurate.

ZDZ's are pretty sensitive to ignition timing so you'll want to mess around with that a bit. First move I'd make is to retard the timing a bit. Next part, and I've not had one of the new engines, is that ZDZ's get hot pretty quickly when running on the ground. Get a thermometer and check between the two top cylinder ribs. If that thing gets to 200 degrees F, you're wasting your time beyond that point. You'll have to shut it down and let it cool off before you try again. I suspect this is the problem you're having; the engine is just getting hot because it's their nature and this one is going to be tight with all the new parts.

I'm going to include a couple of pictures for you, I cannot find the ones RC Showcase put out right now, but if I find them I post them in this thread.

Take a look at where the pickup is in relation to that case rib. The picture you posted looks good.
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Old 10-03-2019, 12:04 AM
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Hi
Are you sure the rotary valve is mounted correct?
On the 180 it’s possible to get incorrect timing if the rotary valve is flipped 180 degrees.
Or maybee it’s overheating as mentioned earlier.
The prop feels a little small I think.
I flew my ZDZ 90 on RE3 pipe with Engel Super Silence 28x12.
//Mikael
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