Anyone know the factory needle setting for a OS 40 FP? Not sure if this is the right spot for this...
Thanks

Open it 3 1/2 turns and start. Lean out as required.

The instructions that came with the engine say 1 1/2 to 2 turns.

Split the difference....I'll try 2 3/4 and see what happens.
Thanks....

I had to start over on Sunday too, and 2.5 for me was right, but that was with a Pitts muffler.
Good luck,
C

Thank you. It is a new motor. Well, it's an older motor, but never fired. Bought it from someone on a Superstar and just wanted to make sure to break it in properly.

I have a PDF of the FP series manual. If you send me PM with your e-mail address, I will forward it to you.

Nicer than the LA (IMHO).
I've had one since 1983 and it still runs OK. The idle behaviour (5% nitro, 18% oil, sea level) is just super. I used 3 1/2 turns for first start.

Thanks Chuck. Just sent you a pm with my email address. I really appreciate it.

If you have an early version of the .40 FP, you will need to run a fuel with castor oil and run it very, very rich for the first 45-60 minutes. The early versions had the iron alloy piston running in a steel liner, and they'd take a while to break in. Once broken-in, though, they were super, super engines with ultra-reliable running habits.

You can tell if you have one of those if they tend to quit as soon as you try to lean it during the first 10-15 minutes. They did not at all like to be run with fuels that had all-synthetic oil packages.

Starting points are 2-1/2 turns out from closed on the high-speed needle, and the air-bleed screw set to block the air-bleed hole 1/2-way. You then adjust as necessary.

Shanet, my os 40 fp is set at 1 1/2 turns. Only needs ever is between warm & cold weather.

Shanet, I definitely second what BAX said. This engine is one of the smoothest, most powerful .40 I have ever run. At least use a fuel with a castor blend for lubrication, and give it plenty air time rich, then lean it after each tank. If you break this engine in right, it will serve you very well for a long time!

Most powerful? You're kidding right?

Not kidding...I say what I mean/mean what I say.
Of the.40's that I had, It was the best.

Exclude the AX.46 of course. Just the .40 size.

Now you can tell us about all the other .40s that blow it away.

The FP is a very nice handling engine, but it's no powerhouse. Mild timing (even by OS standards) and it's small carb inlet make it so easy to operate and tune, but severely limit it's power. I can't think of any engine with less power made in the last 40 years other than the LA series.

i have one and it runs just fine, it isnt a powerhouse but it doesnt seem to mind big props. i have a apc 12x4 on it (10500 rpm), it spools up just fine and runs well in general. it will, quite literally, idle all day long. it hardly uses any fuel (6oz in 30 min about half throttle) but it will leave a HUGE mess all over your plane.

Ooh, you should have tried a Merco.

As you observed though, lovely to operate, quite economical on fuel.
Thinking back, I did use castor fuel at 20% for the first 5 years of its life. I use ML70 now which produces less mess.
The Irvine Sport 40 though just blew the socks off an OS40FP.

Well I do have a twin plug Merco .49 that I haven't ran yet, for a vintage project.

And I do like the Irvines. To bad they are no longer made (in England).

(4) .36
(1) .40
(1) .45
(3) .53

I guess I like the Irvines a lot. Maybe the best sport motors ever made.