Run a search on this forum and the udder forum. See if you can find the information you request. Engines can be run effectively stock. This topic comes up almost as often as issues relating to BOM.

The "runaway" problems were from the early usage in trying to run them like Fox .35s.   They do not like to run a low rpm 4-2 in stock trim.  If you tried to do that, you would get to about the square 8s and it would hit passing gear and never return.  It's a wild ride with a larger full blown stunter going from about a 5.2 lap to about a 4.5 lap. 

High rpm, low pitch works best on an out of the box one.

Big Bear

Hi Allen

No It is not too much motor, many of them have been used in Noblers

Regards
Randy

Thanks to all,

     I look forward to running this engine.  I think I will try an 11/4 prop and keep the rpm's high.

Keep away from the Control line stock muffler, the exhaust hole is tiny and will make for runaways. Use a good open tongue or tube muffler

Randy

I got in my first 4 flights with the OS 40FP.  Quite an engine.  It is a bit fast.  I was using a Top Flite Power Point 11/4 prop at first.  Then it broke and I used an APC 11/4.  The first flight, it ran pretty well. Then it stopped after 2 minutes on flights 2 and 3.  I finally checked the fuel filter.  It had a ball of something in there. I'm glad I used a fuel filter in that one.   The fourth flight was pretty good but still ran pretty fast.  I was running without a muffler.  I have a tongue muffler and a possible head shim on the way from Randy.  I hope to tame it a little.  Randy also said to cut back to 5% nitro.  I was using Brodak 10/11.5/11.5.  I've obtained some Powermaster 1/11.5/11.5.  I'm wondering if just adding the muffler and lowering the nitro will make it more stunt friendly.  It seemed to almost burp on outside loops but not like a Fox.   I like the power.  I plan to try some different props.  I have 10.5/4.5 APC, just one and several Zinger Pro 11/4's.  I haven't found any 11/3's. I did look at Brodak as I was there the Saturday of Fly-in.  Nice to meet some of you in person. 

Beware of adding extra head gaskets if you are using factory OS parts. The OS gaskets are 0.016" thick. For the stroke of the FP 40 and the others with the same stroke, 10° of crank rotation at TDC gives 0.0055" of piston movement.

Adding a second 0.016" gasket can play havoc with the ignition timing. Some people have had success taming the FP 40 by using the venturi from the FP 20/25 (6.55mm dia).

But as Peter said, only change one thing at a time.

Ignoring my own advice, I ran an ABN FP 40 a couple of weeks ago—first flight on a new model, first flight on an engine that I had previously only run on the bench.

The initial setup is the FP 20/25 venturi, hemi head per Bob Zambelli's modification with a 0.010" head gasket and APC 12.25" x 3.75" prop. The tank is a Sullivan S-6, setup with a clunk and uniflow. The engine speed was rock steady for the first half flight with no run away after each manoeuvre. Half way though the flight, the speed picked up several hundred revs but then stayed steady at the higher speed without running away. Those watching thought it pretty a impressive engine run.

I want to report that I lowered the nitro content of my fuel on a tip from Randy.  I didn't yet add a shim though I have one.  This motor is running wonderful and has gotten me to the best flying I have ever done.   I'm having fun! Currently it has a 10 3/4x4 APC prop.