Author Topic: OS 40 FP RC conversion? (Read 1200 times)

Allan Leonard · « **on:** January 24, 2018, 09:11:26 AM »

Just wondering if the venturi and needle valve assembly is available, and from who, so I can get rid of this RC carb?

Thanks,
Allan Leonard

Geoff Goodworth · « **Reply #1 on:** January 24, 2018, 01:46:50 PM »

The final decision probably depends on who is nearby.

All you need is a venturi and NVA.

Start with the FP 20/25 venturi from Tower and the FP NVA. Both are drop-in. Despite what the Technical Notes from Tower say, all that I have bought from them measure 6.5mm ID.

Heat will help with the two screws that hold the carb in and the screws are JIS so if you don't have a JIS screw driver, you need a new Phillips head screw driver, a well supported engine, plenty of pressure and a steady hand. Have your soldering iron on hand to heat the screws and break the thread locker that they use.

Run the engine with the FP 20/25 venturi and see what you think. If you are unhappy with that, try reaming the bore out to 17/64" ID (6.75mm ID). 6.75mm is the ID of the small venturi that used to be supplied with the FP 35 and 40 in the early days of those engines. It's only a very small increase in ID so I don't bother with enlarging the inlet or outlet. I would not be quite so cavelier if the increase was greater.

The attached article was published in Stunt News some years ago. You may find it useful.

RandySmith · « **Reply #2 on:** January 24, 2018, 07:11:55 PM »

Quote from: Allan Leonard on January 24, 2018, 09:11:26 AM

Just wondering if the venturi and needle valve assembly is available, and from who, so I can get rid of this RC carb?

Thanks,
Allan Leonard

I have them in stock

Randy

Allan Leonard · « **Reply #3 on:** January 25, 2018, 10:48:20 AM »

Thank you Geoff, very much appreciated. Thank you Randy, I'll be in touch.

Allan Leonard

Jim Carter · « **Reply #4 on:** January 25, 2018, 02:06:36 PM »

Hi Allen! Just curious, have you ever run the engine before? Not to come against Randy, why spend the money when you could easily lock the throttle open using the throttle set screw. Personally, I have found them to be very strong, reliable engines that run very well at full throttle. As a result, I just lock the throttle in the wide open position and run them like that. I have them locked open on a couple of my Ringmasters, as well as twin OS. 25 r/c's, locked open on my Grumman Albatross and two Enya .09's locked open on my Lockheed SP-2H Neptune and an OS .15 r/c locked open on my Perky! I've not had any problems performing any suitable stunts or maneuvers as appropriate for the specific plane.

Allan Leonard · « **Reply #5 on:** January 25, 2018, 02:25:55 PM »

Hello Jim,
Yes this engine powered about six different RC planes back in the 80's and it performed flawlessly. It hasn't been used since, stored pickled in Boeshield T-9 and in a ziplock bag. I have given some thought doing just what you suggest but to put it simply I just want to get rid of the RC look.

Thanks,
Allan Leonard

Jim Carter · « **Reply #6 on:** January 26, 2018, 12:32:56 PM »

Quote from: Allan Leonard on January 25, 2018, 02:25:55 PM

I just want to get rid of the RC look.

Okay, well I s'pose Randy is who you want to talk to!

Air Ministry . · « **Reply #7 on:** January 27, 2018, 07:25:12 PM »

the LA / FP 20/25 ones the same . more or less .

My Experiance with FPs leads me to believe pulling the backplate will show you if theres a big lump of grunge on the crank web .
Before it feeds itself through the finely lapped piston / liner fit .

Author Topic: OS 40 FP RC conversion? (Read 1200 times)

Allan Leonard

OS 40 FP RC conversion?

Geoff Goodworth

Re: OS 40 FP RC conversion?

RandySmith

Re: OS 40 FP RC conversion?

Allan Leonard

Re: OS 40 FP RC conversion?

Jim Carter

Re: OS 40 FP RC conversion?

Allan Leonard

Re: OS 40 FP RC conversion?

Jim Carter

Re: OS 40 FP RC conversion?

Air Ministry .

Re: OS 40 FP RC conversion?