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Author Topic: OS FP 40 Problems : Advice Please !  (Read 1246 times)

Offline Robin_Holden

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OS FP 40 Problems : Advice Please !
« on: July 13, 2009, 12:35:12 PM »
Greetings all from a steamy S.W.France. Advice required please to help me sort out my NOS O.S 40 FP .

The story so far ...... Please bear with me !

An un-run and pristine OS40 FP from my collection was brought out of stock and sent to someone highly respected to be 'worked over' and made into a usuable stunt engine.

It is the old steel liner version , so when I got my engine back I started to run it in on my bench , or I am still trying to !

It has had well over TWO HOURS of running-in time so far using fuel with 24% lube [ 17% synthetic , 7% castor ].

Each run was around 4/5 minutes , rich [ around 7,500 rpm ] and used a 10x5 Master Airscrew prop' , gradually leaning out a tad but NEVER lean.
Each run had a good cooling off period.

I then tried to test a few props :
It appears the OS will only accept a 10.5x4.5 APC at around 8,500 in a fast 4-stroke before it runs away !

It is very needle sensitive and still appears to be 'heating up' , and just won't accept any 11 inch prop apart from an 11x4 at a rich 4 stroke.

It is also taking an age to cool down  between runs. I can't keep on running it in forever or should I ?

So ....Do I need more oil , perhaps all castor .......I've tried 3 different NVA's and 3 different plugs !
Any suggestions will be really appreciated !

Just as an aside I have a perfectly mannered 35FP  and a Tower 40 both having been modified for a better stunt run so this is not my first experience.

Much obliged ,

Robin [ ex-pat Brit in the Charente full of ex-pat Brits ]
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Offline Mark Scarborough

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Re: OS FP 40 Problems : Advice Please !
« Reply #1 on: July 13, 2009, 04:12:38 PM »
Robin,
From what I have seen, the old version FP 40 didnt need anything to make it run well.
what size venturi are you running on it? I kind of wonder if it may be to big a venturi, I recall that I was running a .275 on mine, with the supertigre style needle assembly. I also ran 11 and 11.5 inch props in the 4 pitch range. I wonder if your break in methods may be part of the problem.
My tendancy is to run a small flat pitch prop that lets the engine get up to the rpm you want to run at, ( say 9400) with no load, heat the motor for short runs about 2 minutes, and cool it . repeat until it will hold a nice needle. I seem to remember using about a half gallon of fuel. Then start running longer deeper pitch props.
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Offline Martin Quartim

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Re: OS FP 40 Problems : Advice Please !
« Reply #2 on: July 13, 2009, 06:29:49 PM »

Hi Robin,

I wished you had tried the Philly Setup before sending it to be modified.

 Now I suggest you go back to the highly respected some one who worked on your engine and ask how to setup the engine.

Mostly reworkers detune the engine so you can use higher pitch props for distinct 4-2-4 run.

Martin

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Offline Steve Helmick

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Re: OS FP 40 Problems : Advice Please !
« Reply #3 on: July 13, 2009, 08:23:52 PM »
"It is the old steel liner version , so when I got my engine back I started to run it in on my bench , or I am still trying to !

It has had well over TWO HOURS of running-in time so far using fuel with 24% lube [ 17% synthetic , 7% castor ].

Each run was around 4/5 minutes , rich [ around 7,500 rpm ] and used a 10x5 Master Airscrew prop' , gradually leaning out a tad but NEVER lean. Each run had a good cooling off period."

Note: Steel liner  At least for running-in...I'd reverse the oil contents...17% Castor and 7% synthetic, and might increase the castor content to 20%. 

Cut the prop down to 9"...or 8"! Balance it carefully, but leave the tips thick and square. Let it rev to 10k. Less load, more fuel, more oil, more cooling, makes for less heat in the engine. You're NOT running with the muffler???? Don't, if you don't have to. If you must, just setting a cardboard box behind the engine will cut the noise a lot. Add eggcrate stuff, cardboard baffles, or bubble wrap, if you need more noise suppression.   y1 Steve

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Offline L0U CRANE

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Re: OS FP 40 Problems : Advice Please !
« Reply #4 on: July 13, 2009, 09:46:02 PM »
Robin,

...gotta go with Steve on this... Steel liner went with cast iron piston. That means (most often) need for ample castor in the blend. It is NOT an ABN engine! The high-synth/low castor fuel is best for ABN/ABC/AAC engines - but preferably 10/10 or 11/11 (castor/synth) for eventual stunt CL use. For break-in, I'd prefer a 25% all-castor oil fraction in a  5% to 10% nitro fuel for your iron in steel engine.

RPM on prop sounds a bit anemic, too - as does heating enough to require a longer cool-down. Castor does several neat things: It doesn't burn, so it leaves the exhaust with the heat it absorbed inside the engine - that's cooling! It remains lubricating, since it doesn't burn. It takes some of the volume away from the fuel ingredients that DO burn - that's indirect cooling, since less heat is produced from less that can burn.

Castor also does a weird thing - it runs TOWARD the hotter metal, not away like petroleum oils do. At least, this means castor draws into the hot metal areas that need lubrication, better than a petroleum oil would do. Synthetics DO burn at lower temperatures than castor, which adds a bit to the heat released by combustion. and changes them from lubricants to combustion by-products. Little of them is left to carry absorbed heat out the exhaust...

So,if you can, set up a 25% castor fuel, and run a bunch more beak-in short runs. THEN let us know how its' going?


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Offline Robin_Holden

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Re: OS FP 40 Problems : Advice Please !
« Reply #5 on: July 14, 2009, 12:56:23 AM »
Guys .......I'm VERY much obliged for all your contributions.

I'll be following your advice to the letter !!

Must go , it's a public holiday here today , July 14th , the 'Fall of the Bastille' during the French Revolution.

We need one of those back in my homeland , Britain , to get rid of those neo-Marxist nutters pretending to be 'Caring Socialists ' and bankrupting the nation with debt !

Sorry for the rant !!

Thanks a million ,

Robin.
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Offline Geoff Goodworth

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Re: OS FP 40 Problems : Advice Please !
« Reply #6 on: July 16, 2009, 04:27:18 AM »
Martin

What is the Philly setup for the FP 40?

Regards, Geoff
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Offline Martin Quartim

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Re: OS FP 40 Problems : Advice Please !
« Reply #7 on: July 16, 2009, 08:02:20 AM »
There was a big debate a few years ago about the 40FP and the text below is what I took note and tried to see if works, and it does very well indeed. I have to apologise because I don't remember the name of the author of this message.

=========================
Philly setup for 35/40FP

One or Two extra head gasket
.283 Venturi with OS Original Spray Bar
Aeroproducts Tongue Muffler
APC 10,5x4,5 or
5-10% Nitro 22% lube(50/50 synthetic castor)
Hot GlowPlug
Non uniflow 4.5Oz Tank with pressure. ( I used a Brodak Uniflow and cap the uniflow and pressurized the overflow vent)

Set it in a 2cycle. Should sound fat and happy and somewhat loud. If engine runs away and fuel consumption is low. Open up the exhaust more and perhaps venturi will also need opening to compensate for the thickness of the ST needlevalve. Best of luck. Tell us how it goes.

======================================================

I tried this with an 35FP and it works amazingly well. 

Too bad OS stop making the FP engine and most parts for it is no longer available.

Martin

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Offline Andrew Tinsley

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Re: OS FP 40 Problems : Advice Please !
« Reply #8 on: July 16, 2009, 08:50:11 AM »
Hi Robin,
             Thanks for the very interesting thread on your "Awkward FP 40". I learnt a lot from the replies! However it was rather spoiled by your political rant! Do us all a favour and keep politcs out of this great hobby of ours! I don't care if people are marxist through to fascist as long as they keep it to themselves!

Regards,

Andrew.
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