Reverend

My Feedback: (3)

ok, short status my side. the 7-77 has 90 minutes of break in time and i de ided to give it the beans for the first time. high speed needle still 4 turns out so rather rich and prop is a 22x12 Graupner Sonic. I tached three times and it is doing 6150 rpm!! Idle is stable at 1450 and sounds like real ear candy. No glow support.

I think I will switch to a 24x10 fiala prop now.

great little engine this!

rev

movonzez

Hi Tom! Thank you very much for your answer. Unfortunately I had no chance yet to test it. The mid range an the full throttle settings seems to be rich enough, the engine accepts throttle changes from low to high very smooth an without delay. My problem occurs when I reduce throttle back from high or midrange to the idle position. When doing this, the rpm break in and in the end the engine stops. When I play a little with the throttle in this unreliable position - lets say in the lowest 15 % of the total servo-throttle range), the engine stabilizes and keeps on running. In the end, this is no circumstance to fly with a good feeling, because the danger of a sudden engine stop is given and if the idle throttle settings are adjusted to a level where the engine runs stabile the rpm level is much too high. But at first I'll try to set up the engine as you mentioned keep hoping that this might be the solution. Thanks very much again - I'll report about the result! Moritz

movonzez

Hi Tom! Today I had the chance to test the engine and try out several settings. I found the problem causing the idle engine by far too high and unreliable. The onbord glow system (Microsens Glow7) was set to maximum power, so that in idle the glow current was too high (during operation mode after pre-start-glow). The engine was running even with throttle closed totally!! The devil knows from where the engine gets the oxygen (probably from the 5 % Nitromethane or gaps in the sealing) to run. Then I disconnected the glow-LiPo and - wow - the sound changed immidiatly and the the rpm dropped about 300 - 400. Now the engine turns low and reliable without shaking the model at idle throttle an I'm able to stop it by closing the throttle. I lowered the glow-current-setting about approximately 70% and now the engine runs like I think it should do. I never thought that this would have had this massive effect! Best regards, Moritz

northrcer

I have been running in a 735. I have 2 hours of run time on the engine. I am now using (for the second hour) Cool Power 15% Nitro and 18 % oil cut 50 - 50 with methonel.
The engine runs from 1500 idle to 2/3 power very nicely. Responds nice and is running a bit on the rich side (Confirmed with the pitch test on the fuel line. Engine gains a little RPM the dies) from 2/3 power to full throttle the engine starts to go lean. At full throttle which I have set a little back from full throttle (as per the disscussions on this forum from Maxim) I have to have the highspeed needle full out for the engine to continue to run. When I do the pinch test on the fuel line the engine confirms that it is to lean and will just quite with no rise. I cannot tune it like the manual says. Lean to peak and richen 10 % of max RPM. Any suggestions would be appreciated.

Maxam

My Feedback: (62)

Moritz, Glad to hear of your successes!

Northrcer, My 735 was similar. Add more ethanol to drop the oil down to 8 or 7 % which will effectively richen your mixture! Also on mine I had full throttle set to 5/8's open. -Tom

northrcer

Thanks Tom,
I will give that a try.
Have you heard of anybody trying to up the size of the main fuel passage to suppy more fuel?

njmheli

Hi Guys.

Just found this "thread"........Think it is great,lot's of very useful information and comments,have been reading it for the last couple of days !!!

I have a 777 on order + collector ring at the moment,so being a Corsair nut,it has got to be put in the new H9 60cc ARF Corsair,which I hope will be available here in the UK soon.I have started to get all the various items needed for this radial ( I have Saito FA 200R3 in a T/F S/W.......runs very well ),I have opted for the Mcd 477 on board glow,which I received from Sonic in the US last week.( Great Customer service and communication by them,product looks just great,will be using it with a 5000mAh Nimh pack ).

I have been building a T/F giant Corsair for the last 7 years ( I'm not a slow builder,but have been doing other projects aswell !!,she is about 80% finished,looks as if it may now be a while before it is completed..if the H9 comes along !! ).I have a BNIB Saito 450 for her.

Back to the subject in hand....The lovely 777.......I have also a Solo 3BL set up for the Corsair ( which I was going to use on the T/F set up ),so I was thinking of using this on the 777,the prop being 22" x 10 x 3,obviuosly I can adjust this pitch setting.......Will this be OK on the 777...?

The other items I have been looking at are : After run oil ( i use at the moment Model Technics A/R oil) ,but as Blue-Block is available from HH here in the UK,will be using that : Air tool oil,will be getting some of that and also the oil for the rockers,will probably use some Chain oil from STHL..?

I have a Test Stand built and will do all the running in on that,so when the airframe is completed,mount and fly !!! I also have a "Laser" Thermometer to see how the cylinders are doing when running...

I have a couple of questions for you all,hope that is ok,would appreciate your comments !!!

1/..........I will not be using the "pressure" feed to the tank from the collector ring.

2/..........To mount or not to mount,using the "ali" standoff's....? I have seen a few installations and all bar a couple are using the standoff's.As far as torsional forces go,surely the steel bolts,if using hollow standoff's are more than up to the task ???

3/..........Push rods being loose and falling out.....common or not..?

4/..........Side play on the rockers,common issue,any problems...?

5/..........Looks like,checking the valve settings a must from new out of the facory and using the method stated by "Tom" !!!

Thanks in advance to all and I hope to be able to post as my project gets going....?

Kind regards............Nick (UK).

Maxam

My Feedback: (62)

Nick,Tom here, so here we go;
1. I do not use pressure either, but I use "fat" fuelline including the tubing through the tank as well as a very short run. 2. Ypu are a builder, build a nice wood standoff out of balsa and ply. Much more solid. 3. I have never had a pushrod fall out. My 9-90 is up to flight 120. I also have the seven like yours in a corsair and I believe I am at around flight 60. 4. Side play is funky but I have not seen any problems. 5. Yes I would! Look earlier in my thread at the corsair. I am using a Xoar 22x10 three blade warbird prop. I like some nitro but I do not use onboard glow. Welcome Nick! -Tom

njmheli

Hi Tom.

Thank you for your welcome and your valued reply !!

I already have the large bore silicon fuel tubing ready,along with the large bore "sullivan" fuel filter and large bore brass tube to go in the tank.I also have purchased a "ceramic" type fuel tank clunk with a large bore feed tube,to match with the fuel system.........oh and also a large bore Dubro fuel filler valve ( which I intend to mount on the top of the fuzz,but slightley recessed...where the full-size has it's fill point).

I can then use this filler to shut off the fuel supply to the 777,when I want to starve the radial of fuel prior to using the after-run oil and air tool oil flush out.

Hoping to get the 777 here in a couple of weeks and will post my findings from opening the box along with a test stand run-up..

Many thanks again for your reply,will be looking at your "built-standoff" a bit more !!!

Kind regards.............Nick(UK).

Linkan2

Hi
accident, accident
My UMS 7-35 is injured by a bang the ground.
a few days after me, a friend hurt his 7-35 very bad.
I hope that horizon hobby release the spare parts for those engines.
I would have to back cap and engine mount, these are not included on the website
Lars

Maxam

My Feedback: (62)

Lars, They have the parts. I believe you have to send the engine in though. -Tom

Linkan2

Hi
I want to buy parts and fix the engine.
engine is disassembled into parts and not much damage.
so I think they are unnecessary cost to mail engine to the U.S..
When I can repair itself.
(Posting 1kg to usa cost more than $ 100)

so I'll just wait till horizon coming out with parts for everyone.

Maxam

My Feedback: (62)

Lars, First I am sorry that you damaged your engine. I would call Horizon in Europe and explain your situation. They might then send you the parts you need. I admit I like to work on my own engines too. -Tom

Linkan2

Hello everyone
Now comes some pictures of 7-35 in parts.
And setting the cam ring

EQ1

Nice and interesting pictures! Can you tell how you removed the front cover incl. crankshaft?I tried on my 9-99 and gave up, because it was very tight and I was afraid to break something due to not knowing how it is fitted. What was the damage on your engine?

Greetings to Sweden!

pappy 883

My Feedback: (2)

Thanx for sharing the pics of your engine. Now I won't be tempted to "I wonder what it looks like on the inside."

Linkan2

Hi EQ1
to remove the cam housing and crankshaft.
remove the backplate and snap ring on the crankpin
yes the front cover is tight, but pressure from the rear of the engine.
then the whole front packetet out.

damage to my engine backplate and motor mount also pushrods.
crankshaft was a little bent but I've adjusted, to straight

There will be more pictures soon
Lars

EQ1

Hi Lars!

Thanks for sharing your experience. I am about to disassemble my engine, because of the strange "clonk" noise every eighth revolution. It runs OK so far (havinh 1.5 liters through) and Horizon in Germany said it is known and of no matter, but looking at your pictures I have the feeling that there might be a broken or damaged tooth ...

If you are about to replace the push rods I propose not to buy them from Horizon directly. I got mine from Phil's Hobbyshop in the US, very inexpensive. There is also a company in GB selling them much cheaper.

Hope to here from you that the engine is running again. I am looking for a 735 right now for a new project ...

Regards

Olaf

Linkan2

hey Olaf
here are some more pictures of the assembly of 7-35.
I have found a site in England that has parts at great prices.
to EVO / UMS engines
http://www.wheelspinmodels.co.uk/c/606/?p=5

you may well take some pictures of your damage if any.

Maxam

My Feedback: (62)

I would like to report on my crankcase ventilation system to prevent corrosion in these engines. (Refer to post #797) After 4 more flight sessions and using an aquarium air pump to dry out the crankcase each time the engine had absolutely no corrosion and the prop turned over smoothly, even several days later. I am very happy with these results. No more worries! -Tom

Lars I am happy to hear your engine will be together soon. I just ordered a new 7-35 for myself! -Tom

Sundownee

My Feedback: (30)

Hi, which AT6 Harvard did you put your 735 in, I have one also but I am getting ready to maiden her.
Mine is the Kmp version , I am worried about weight and maxium engine rpm, 5675 on a 18x8 prop
Thanks
Paul

cymaz

Wheelspin models are very good. Also if you know the part number then try PodiumRC in the uk aswell.
As for fuel mixes, I have now started to use Model Technics ProPower16 cut 50/50 with methanol. My 7-77 seems to like it alot.

movonzez

Hi Paul,

my AT-6 Harvard was built by Black Horse Models (.120 size). Actually, they picked this model out of their sales programm. The only necessarcy modification is to throw the retracs into the trash can, after they collapsed at the first flight. I replaced them with the Ladotech RS333 electrics and now everything is fine. The Zero Fuel Mass is about 6,2 kg. The enginge runs with a Biela 18x8 Carbon Propeller and with 93 % Meth + 7 % Aerosynth3 Oil. In the end, the power/mass ratio is about 1:3, so that you haven't to expect a performance marvel, but for scale flight it's absolutly sufficient. Straight and level flight with about 1/3 to 1/2 throttle suits perfect to this aircraft/engine combination.

Best regards, Moritz

Maxam

My Feedback: (62)

Well folks I was helping someone local with their new 7-35 and it ran so well, much better than my old UMS Seidel one. I saw the 10% off deal at Advantage Hobby so I picked up a new one for myself. What a difference! The carb works properly, able to deliver fuel on the rich side at full throttle. I was at first disappointed to find no more OS type F plugs supplied and tallish plug connectors. Well let me tell you the new plugs work very well. After about a gallon of breakin, I set the idle to 1200 rpm and walked away. I came back 20 minutes later and all 7 cylinders were still firing! (no glow heat mind you) The engine was broken in with a XOAR 17x8 prop which in practice I find to be too small. I tried a SEP 18x10 with excellent results with a full throttle of 6000rpm. The engine runs smooth at all speeds. This is one sweet running little engine. -Tom

Sundownee

My Feedback: (30)

Tom,
What fuel did you use and what is the brand of plugs come with engine now. I picked up the new updated carb from evolution, which I believe should've been free to correct the throttle problem.

Thanks