TimC

4000' Elev., 70 deg., 15% Powermaster, "F" plugs, 16x8 MAS. This is an old engine (air bleed carb) bought used many years ago, and not run for about 7-8 years. Peaked at 8300 rpm.

PlaneKrazee

My Feedback: (14)

Tim,

My newer 160 Gemini is running a APC 17X6 I'm getting over 9000 rpm on 10% nitro. Very good engine!

TimC

This is the first big engine that didn't shake my test bench. I have a few more big props I'd like to try, but no 12mm reamer. I have a wood 18x5 that would look scale on the 140 Cessna that came with the engine. I'll post the r's when I am able to ream it.

PlaneKrazee

My Feedback: (14)

A friend has a new engine on a scratch built Fly Baby with a APC 18X6 and loves it.

promag

Hi
My is a new one (less than a gl of fuel) and turn APC 17x6 8200 with wildcat 15%N. Thrust is 13 lb. Pull my H9 TCRAFT scale like (not vertical).
Try 18x6 Prozinger and get 7200 rpm. Not good.
Needs more running time for brak down.



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TimC

Nice looking plane promag. Who makes the engine mounts? One more question: It's starting to get cold here in the mountains of California. Would you like a house guest for the summer down there?

promag

Hi Tim

You are welcome! The mounts were made private.
Yea, summer is comming. We fly all around the year. The shots are in my little farm where I have a short (400 ft) runway and 20 planes.
Near 12 hours, the sun starts to burn and I dive in the pool
After that, a nice barbecue!]
Nice life we have here in Brazil!

Regards

PlaneKrazee

My Feedback: (14)

Those rpm should be up after a gallon of fuel. Did you heat cycle it on a test bench for break-in?

I think that is how I got the 9000 rpm out of it. Every engine I have broken-in with short 5 minute runs with cool downs and gradually leaned out to peak after 1/2 to one gallon has always proven to be an excellent runner.

TimC

Skypilot_one, this is an old engine. It was bought used by my friend with unknown hours of running time. My friend ran it quite a bit years ago. It had been sitting idle for years. I did do a few heat cycles very rich to try to make it realize the vacation was over and it had to go to work again. Brian, after re-reading these posts, I realize you were replying to promag.

PlaneKrazee

My Feedback: (14)

Tim,

You can always send the piston and liner to Frank Bowman. He can hone the cylinder and fit the ring. Other than that you could polish the valve seats with some water soluble compound. Your engine would be better than mine for about $20.00-$40.00!

TimC

Skypilot_one, this engine is in a 140 Cessna. If it's down a little on rpm's, it will probably still work o.k. The compression seems fine, and I can't hear any hissing through the exhaust pipes when run though the compression stroke.

PlaneKrazee

My Feedback: (14)

You will really enjoy the engine, they run flawlessly.

Johng

My Feedback: (4)

Hi guys:

A friend of mine just bought a 108" cub with a 160 Gemini on it. Flies OK, but the engine makes a pretty rude clacking sound at high throttle. We both have run 4-strokes before, but not a lot. Never a twin. We inderstand that the engine should just be leaned from rich but no more. So, at one point, the throttle was blipped up high, more clacking, then a backfire and the prop spun off. THis is using 12% nitro, 20% oil sport fuel. We are still trying to figure this one out - we may just need to clean the carb....

Any suggestions?

mipo

Aloha guys

I am new in the forum.

I have an O.S. FS 1.60 Gemini. It turns MenzS 18x6 at 8.000+RPM an gives 6.5kg of thrust. I like the engine very much. I powers Giles 202 with wingspan of 1650mm.

Bye

Milos

TimC

John,it sounds like it's mighty lean on the high speed needle and you're getting pre-ignition. If opening the needle can't create an over-rich condition, I agree it sounds like a restriction somewhere in the fuel delivery. An interesting item from the manual is that O.S. advises against starting one cylinder, then switching the glow lighter to the other. I guess this causes undue strain somewhere.

TimC

Welcome to the forum Milos. Is your Gemini the new one with the twin needle carb? I have a wood Zinger 18x5 that I will try as soon as the 12mm reamer I ordered arrives.

Johng

My Feedback: (4)

Yup, it's one of those deals where you buy a flyable airplane - what do you do then - you fly it. Now we have the cowl off and will take a closer look. There may be an air leak somewhere, or a cracked fuel line, or old glow plugs. Who knows. Time for a full check-over.
The plane has on-board ignition, so no worries on the startup procedure. Former owner said the glow was usefull for when the engine lost a cylinder. It's on a switch...

Where can I find out about adjusting the valves? What do out-of-spec valve adjustments do to the engine run?

TimC

John, the 160 owner's manual says to refer to the valve adjustment instructions in the tool kit, which I don't have. Here's William Robison's quote: "The book says 0.002" to 0.004" clearance. Tighter clearance gives better peak rpm." I set mine at .003" and it runs fine. Hopefully someone more savvy than me can help with the symptoms of out of spec valve lash.

TimC

I finally received the 12mm reamer I ordered. It's a Fox and the handle is removable so you can chuck it in a drill motor. Here's are the r's from two additional props:
4000' Elev., 70 deg., 15% Powermaster, O.S. "F" plugs 17x6 APC.......................8640 peak rpm
18x5 wood Zinger...........7830 peak rpm

Johng

My Feedback: (4)

I adjusted my friend's valves, then moved on to check the fuel delivery system, and realized there is no muffler pressure hooked up. Just a vent line. Do I need muffler pressure with this engine? Would it hurt anything if I hook it up?

John

TimC

John, my engine has straight pipes and no mufflers. A Perry vp-20 pump was installed and the tank is just vented to the atmosphere. I think using muffler pressure on the tank would be a good idea if available. This should let you over-richen the high speed needle easily.

PlaneKrazee

My Feedback: (14)

Tim,

That sounds good for an old used engine.

mipo

Tim, I'm sorry I have overlooked Your question. Yes I have the engine with Two needle carb. Yesterday I have flown my Giles with this engine on MenzS 17x6. It gave 7.950 rpm and 5,5 kg thrust. Good enough for ship with 4,6kg.

Milos

mipo

I have tried three props with the same size(18x6) but different make: Mejzlik, MenzS in Biela. The results are:

Engine: OS FT 160 Gemini (OS F plug)
Fuel: Cool Power 10% nitro
Air temperature: 6°C
Humidity: high (~90%)
Wind: 0

Make; Size; Speed; Thrust; Price; Weight
Biela 18x6: 7.450rpm 5,80kg 29,90€ 88g
MenzS 18x6: 7.750rpm 5,95kg 10,90 € 66g
Mejzlik 18x6: 8.450rpm 6,00kg 43,90€ 92g

I like Mejzlik the most.
Milos

PlaneKrazee

My Feedback: (14)

Anyone else running this engine?