OS .35FP question

LAST EDITED ON Oct-09-03 AT 02:49 PM (CDT)
 
I recently started using my OS FP and I am getting a very inconsistant run. Can anyone suggest simple mods that can be done to help with make the engine run correctly. Any information is greatly appreciated! I am an engine novice so please explain what and how to do the mods. Thanks in advanced. I am using this engine on an ARF Nobler. 11 x 4 prop.

Kris

LAST EDITED ON Oct-09-03 AT 02:04 PM (CDT)
 
I'm sure someone in here would know how to contact Tom Muggleton? His modifications to the 40FP made a totally new engine out of it .. in many ways comparable to the original ST46 in it's constant runs.

Here's his email addy anyway .. [email protected]

You need to give your application-what plane are you flying? There are several ways to skin that 35FP, and all will probably work. Here are some suggestions:
1)Go with the flow. Get a low pitch large diameter prop (11-4 for example) and run the engine at 11-12 krpm or so---or in the manner that OS expected it to run.
2) Add head gaskets, smaller venturi to see whether you can get it to do the 4-2-4 dance. I know some who have done this with the "Box Stock" FP.
3) Fill the boost port (or better yet contact our host Len to have him make his mods) to set it up for big props and a fat 2 stroke. This version (aka Stuka Stunt) can really power some big planes. See Len's description on the SSW site.
4)Grind at the transfer ports to change the blowdown, according to GMA, the way to tame the beast into a gentle 4-2-4 mode.---maybe best to contact a engine rebuilders.

I am sure others will add in.

Filling the boost port improves the engine and is simple to do. If your up at the field this weekend I can show you how. Nice seeing you and your Dad last weekend!

John

LAST EDITED ON Oct-10-03 AT 11:54 AM (CDT)
 
You should be able to make a dead stock fp 35 at least run consistently. You might not like the type of run--but it should be cosnsistent.

Make sure your fuel system is properly plumbed and cleann. No air leaks if it is a uniflow.

with that prop, you should be launching on the ground close to 10,000 RPM. and it should stay in a two stroke all the way--but not go screaming fast.

Tell us more about the set up.

Which os35 FP is it? iron piston or newer aluminum piston? Which muffler did it come with? and what is the muffler now?

Has it been changed from stock? Head shims, venturi, etc? The stock venturi is more than likely too large for consistent stunt runs.

What needlvalve assy?

What fuel? What tank set up?

then...How is it reacting? How are you setting it on the ground and what does it do in the air?

as Johnny-5 said: "Malfunction....need input."

Curt

PS: All the others info is ok...but dont think you MUST modify this engine to get it to be a good solid, and consistent performer. Alot of these mods change the basic running parameters of the engine and also reduce the power available in the process.

You probably wouldn't like the way a Nobler flies with a prop bigger than 11"

Again: What is/isn't it doing?

I went the easy route: since I really liked my Woolard SilverFoxx 40, I asked him to work my 35FP. I really like the results, been using it for 6 years. I found the best results with 10% nitro, 20% half-and-half, Tiger nva, an 11-4 reworked Zinger and launching at 9600-9700 with a stock OS muffler. Very easy starting and consistent fast-4-stroke. It looks like he worked the intake timing and head config and didn't stuff the bypass. Personally, I like the 35 more than the 40FP. One thing: when I was using all-castor, I had inconsistent engine runs, too. Went away when I used a mix of synthetic and a faster needle setting. These engines don't like too much castor, especially when trying to use the needle to get a 4-stroke operation.

Rollin Keszler

LAST EDITED ON Oct-10-03 AT 08:04 PM (CDT)
 
I can attest to Rollins easy starting OS .35 FP. I have held the plane it is in at least 35 times in the last two years and in 29 times it starts on the first flip. Other times two or three flips. Talk about consistant. Just makes me want to throw mine away, or get it fixed.

I have a stock fp 35 purchased at a swap. Ran erratically until we hooked up muffler pressure. Now steady upright and inverted, tends to lean out slightly during a flight, but not much. Haven't even tried a head shim yet. FP 40s and 35s are frequently used in our club for stunt competition through advanced. A head shim, muffler pressure and a good tank, usually does it. Even get break action. Try muffler pressure, 22% 50-50 oil, 5-10% nitro, a few different props in the range you are using. I've just started flying a Brodak Streak with a classic 10/6. It needs some speed to dance. The stock fp35 on muffler pressure seems a good match.

I am using the stock tank that came with the arf nobler and 22% 50/50 castor mix fuel. The engine starts on the first or second flip almost everytime! I would just like to get the runaway problem solved. I am using a 11-4 prop and the lap speeds are still fast around 4.8 - 5.0. It will start off rich and about 5 laps it leans out some then about 10 to 15 laps and it goes even more lean it is a VERY strong engine and it works well with the nobler so I really would like to keep it on this plane just want to it more consistant.