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Engine basics => Engine set up tips => Topic started by: Jim Nohsey on April 04, 2012, 03:40:38 PM

Title: O S 40 FP RC
Post by: Jim Nohsey on April 04, 2012, 03:40:38 PM

Hi, I have an nib 40 FP  RC that I want to use in CL. Where can I get an needle value assembly and venturi for it? Also is there anything else that needs to be done to it for cl use?
Thanks for any help.

Title: Re: O S 40 FP RC
Post by: RDJeff on April 04, 2012, 05:10:48 PM

The folks in the know will tell you to get the venturi and NVA from an LA25, then maybe put in an extra head gasket or two.  That's what I did with mine, but I haven't run it yet.

Title: Re: O S 40 FP RC
Post by: Clint Ormosen on April 04, 2012, 05:21:33 PM

This might help.

http://www.osengines.com/parts/xr13341.html

Title: Re: O S 40 FP RC
Post by: Mark Scarborough on April 04, 2012, 05:59:37 PM

Quote from: Jim Nohsey on April 04, 2012, 03:40:38 PM

Hi, I have an nib 40 FP  RC that I want to use in CL. Where can I get an needle value assembly and venturi for it? Also is there anything else that needs to be done to it for cl use?
Thanks for any help.

Jim,.
there is a lot of information about the FP on here, simply put, if you do a search for FP 40 You will likely end up with a  weeks worth of reading and LOTS of great information..
while I was running FP 40s the biggest single secret I found was lots of castor, and loading it with the right prop

Title: Re: O S 40 FP RC
Post by: Geoff Goodworth on April 04, 2012, 06:04:58 PM

The front mounted factory NVA is available from Tower. Tower number, LXCR49.

Venturis vary but are available from Tower as well.

Some people have success with the stock FP 20/25 venturi in the FP 40. Tower number LXCW99. In the early days of the FP, OS used to supply two venturis, the small one was 6.75mm and the larger is 7.1mm.

6.75mm is mighty close to 17/64" so you can drill out an FP 20/25 venturi to produce the small FP 35/40 part. The large one is still available from Tower as the LA 46 venturi.

I use the factory NVA which is 3.5mm OD and allows everything to screw together. Some prefer the Randy Smith Super Tigre style NVA which is 4.0mm dia. I don't like drilling the crankcase and venturi and, when I run out of factory NVAs, I have access to the ST style NVA with 3.5mm OD. Randy Smith may produce one of those, I don't know.

If you opt for the 4mm NVA, you will need a different venturi.

Title: Re: O S 40 FP RC
Post by: Bill Little on April 05, 2012, 01:18:35 PM

Hi Jim,

Since I am not aware of your experience in C/L stunt, I don't want to insult you.  But, don't expect a Fox .35 style 4-2 run from the stock OS .40FP.  It will probably work best for you with a 11 X 4 prop.  Let it run just into a solid 2 cycle, not completely peaked.

BIG Bear
RNMM/AMM