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Post  DaveyMo on Wed Jul 17, 2019 11:47 am

Greetings:

Calling Rockin' Rusty or anyone else in the know. I'd like just a bit more snort out of this beautiful engine for my Baby Flite Streak on 42 feet of .008 lines. I've got some parts on hand, provided I pirate other, equally beautiful engines. These potential parts include: a dual intake port #1 piston/cylinder; a dual port and dual exhaust slit piston/cylinder without SPI; and a Nelson/Galbreith head.

Ideally, I'm looking for a single modification that would give the most bang for the theft. However any and all other suggestions would be most appreciated as well.

Dave Mo...
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Post  ticomareado on Wed Jul 17, 2019 12:47 pm

The #1 cylinder would be single best hop up.
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Post  Cribbs74 on Wed Jul 17, 2019 2:03 pm

Of the parts you have available I would use the #1 cylinder. The Galbreth head is ok if you shim it correctly, A regular TD head would be what I would use. I have installed a complete top end off of a TD onto a Medallion and it really woke the engine up in the air.

Ron
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Post  Ken Cook on Wed Jul 17, 2019 2:30 pm

You could also shorten your lines a few feet.
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Post  DaveyMo on Wed Jul 17, 2019 4:28 pm

Thanks for the good words, gents. Looks like two votes for the #1 cylinder. I'd like to stay with the longer lines, Ken but will keep that in mind.

Regards,
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Post  ticomareado on Wed Jul 17, 2019 4:32 pm

Also be prepared for more fuel consumption-- maybe 30% more.
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Post  Cribbs74 on Wed Jul 17, 2019 4:36 pm

I think Ken was suggesting that hopping up an engine to stay out on 42ft lines would be the same as shortening the lines and keeping the engine as is. In theory it would be the same speed and lap times would be equal. Generally 35’ is the standard for 1/2A as you probably know. 42’ is used when you have a plenty of power to spare.

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Post  roddie on Wed Jul 17, 2019 5:25 pm

Hi Dave. What propeller(s) are you running on the Medallion? Have you experimented with other propellers? I'm guessing "yes".. but there hadn't been any mention of prop-type or fuel-blend.
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Post  DaveyMo on Thu Jul 18, 2019 11:42 am

Ah, lots of good help being offered here! The additional dope: the prop is a 5x3; it's black and I'm not sure of the brand but I think it came from Cox International. Fuel is 18% nitro and 20% oil blend, mostly castor.

Agreed, 42 feet is a stretch for the Medallion. Yet we do get a reliable number of windless or low-wind time slots in the weather around here. My intent is to try flying on the long lines in anticipation of moving up to a Big Mig .061 ship that I've got in mind. If the Medallion with the #1 cylinder still doesn't cut it, then 30-lb. Spyder line is always around for shorter lines.

Thanks again, gents!

Mo...
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Post  Ken Cook on Thu Jul 18, 2019 2:32 pm

Upping your nitro will help as well. Between the dual bypass cylinder and higher nitro, this will cut the run time down with the current tank
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Post  DaveyMo on Thu Jul 18, 2019 6:27 pm

Very good, Ken. I've got room for a larger tank if need be. Much obliged!

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Post  DaveyMo on Thu Aug 08, 2019 2:36 pm

Thought I'd give this thread a bump and a question. The #1 cylinder is installed on the Medallion body, 5x3 prop, and fuel with 25% nitro / 20% oil. The question concerns break-in time. So far, I've run maybe six ounces of fuel through the critter, and haven't gotten a nice even run yet. Still sputters a bit and varies in speed, though I tached it at 17,500 max. Is the sputtering and variability normal with a new old stock piston and cylinder with this amount of fuel through it?


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Post  Ken Cook on Thu Aug 08, 2019 6:55 pm

Dave, the break in shouldn't take more than a couple of tanks through the engine. However, your other symptoms are a bit of concern. Of course running it a little bit more is not going to hurt it prior to letting it loose on the plane. The concerning thing to me is the sputtering and rpm fluctuation. Are you currently running this on the plane? Silly question but if so, is the engine tight enough?

I would look closely at the piston relationship to the plug landing and insure it's not coming above.

Adding a additional 1-2 head gaskets due to the nitro increase and the fact it's a new cylinder. This could smooth things out and can be removed as needed.

If not currently new, a new plug can cause the erratic running. Just because it glows doesn't mean it's up to the job.

I'm not certain if you ever dismantled the engine to the point of removing the crankshaft. Old castor can become really built up on the shaft and in the bore of the case. This doesn't remove itself from running. A good cleaning is in order in this area as the old castor heats up and acts like a brake on the shaft when running. This can offer the symptoms you've mentioned.

Making 100% sure that your carb body has no cracks on it as well. This can really be responsible for erratic running and poor needling.

In general, make certain everything is properly tightened: backplate, carb body retention collar.
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Post  DaveyMo on Fri Aug 09, 2019 8:52 am

Ken:

Thanks for the input. It's mounted on a Baby Flite Streak. I just checked and found all is shipshape as far a being tightly mounted, etc. Will check out the rest of your recommendations and try the head gasket trick and get back to you. Yes, this is a bit weird.

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Post  DaveyMo on Fri Aug 09, 2019 12:08 pm

Ken Again:

Yup, another head gasket helped immensely. Much better with just a minor amount of sputtering. If I had another one, it'd go on. Instead, I'll try dropping the nitro to 20% this afternoon and see what happens.

Very good insight on your part. Many thanks.

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Post  Ken Cook on Fri Aug 09, 2019 3:22 pm

I think your right on track with the nitro. More nitro usually isn't a problem. That being said, your dealing with a new piston and cylinder which can increase the compression. Shortly after break in though the compression might maintain but it could drop a touch as well. It's just that a over compressed engine can show symptoms of not being exactly happy especially when you start to lean it out. If one head gasket was a improvement, another certainly won't hurt. As mentioned, after a few flights you can remove one and see where your at. It certainly increases the glow plugs longevity by raising it. It could drop the power a little but you can dial it in a little more as far as leaning it to get that power back. This will offer a little bit better of mileage as well.
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Post  --Oz-- on Fri Aug 09, 2019 11:39 pm

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Post  DaveyMo on Sun Aug 11, 2019 1:03 pm

Ken and Oz:

Well, I've finally got it running better thanks to the collective wisdom here! Three head gaskets and 15% nitro suit it so far. Outdoors for the bench run, weather was warmish and very humid. Still just a tiny bit of sputter, but maybe that will take care of itself when it unloads in the air. What do you gents think?

Many thanks!

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Post  Ken Cook on Sun Aug 11, 2019 2:28 pm

I'm thinking it's go time. Report on how it works.
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Post  DaveyMo on Sun Aug 11, 2019 6:40 pm

Oh yeah, Ken it does go! I had it out this evening on the 42-feet lines and she stays right out there. Still kind of sputtery as I didn't take time to lean it out properly. But then I ended up with quite an audience of youngsters and wasn't concentrating on the perfect run. Man-o-man, did they have lots of questions, and offers of "help"! Very fun interacting with the lads and lasses.

i take it that I am aiming for a completely sputter-free run when it's all leaned out? Not sure if I want to drop the nitro to 10%, but could easily do that. Will try again this week and will report back.

Dave...
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Post  dirk gently on Tue Aug 13, 2019 11:10 am

As a homebrewer as well as modeller, I certainly know the importance of hopping up!
Beer Cheers

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