They are fine "out of the box". There are a few things that people have done to make them last a little longer such as Super Tigre bushed conrods. We ran them for years with stock unbushed rods by adding oiling slots to the front thrust face of the rod. Other than that, just be patient with the break in. The piston will "grow" and actually tighten up the fit for about the first half hour then it will settle down. You will be alerted to the final faze by the engine starting to lean out in the middle of the bench run. It will be happily four cycling when it just decides to speed up a bit. Open the valve to settle it back down. When this stops (usually within about 5 to ten minutes of runnig time) the engine will be ready for rich flight with a gradual (over maybe five flights) approach to a good setting. As I said we flew many thousands of flights with this fine old warhorse and I don't ever remember a "run away". Have fun. DaveA

Guys, ignore this entire post or better cut and past it to a discussion of 35 - S characteristics. It was late when I read and posted this. DOH n~Sorry......

Hi Randy ,

Thanks for the info ..

I have a .15 , .20 , .25 , .35 and two .40's .
I've flown the .15 on a Sig Ackrobat (quite fast) and the .40 , on a Sig Mustang (the Mustang was built about 15 years ago with the plastic parts) and the engine had a hard time making the plane do what it was supposed to do
I was thinking of usin the .35 on an Ares

Thanks again for the help

It always amazes me how cheap we are regarding the hobby we choose to relax ourselves. We always expect to buy a $70.00 engine designed to run at peak RPM for R/C folks to bore holes in the sky at max speed, to run like a stunt Fox .35 with twice the horsepower...C'mon folks it ain't gonna happen. You need to get it TUNED if you want it to run for stunt. The object is to go out there on Sunday morning, flip the prop, and have a great flight. Every flight. Every Sunday. The engines we are buying today, are not designed for us. Period. There are those folks who truly know how to mod these engines to do what we need them to do for out activity. Having worked in a shop where these engines were created for almost ten years I know the answers are not simple, despite what some folks might tell you.

The $30. to $50. invested in your engine for a professional stunt rebuild will provide you with YEARS of pleasure and enjoyment. I have watched MANY flyers go frustrated for years over poor equipment, fuels etc...(Sorry to admit it, but myself included!)

Folks, it's just not worth the $avings.  That professional rebuild will cost you 1/2 a days outing on the golf course, and will provide you with 1 - 5 years of total joy.

Really! DOIT NOW.


Ward-O

I've got a bunch of FP's.  I used the 35 and 40 extensively for several years.  I would like to say they're great stunt engines out of the box, and that they work great, etc, but I can't.  They're nicely made, they make lots of power, start easily, etc.  The problem is they do run away.  Many times the needle could be moved one click and the engine would go from too rich to too lean.  There are so many fixes for the FP, that a person can go mad trying them all and never find a solution.  Sometimes they work perfectly but when they don't the troubleshooting flow chart is a mile long.  4-2-4, high rpm low pitch, stock mufflers, tongue mufflers, head gaskets, venturis, NVA's, fuel tanks, glow plugs, fuels, props, vomit.

I've also run the 15, 20, and 25.  The 15 seemed to work ok but it's been quite a while since I've run it.  It was too much power for the Akromaster I had it on. The 20FP is a real gem, take it out the box, set it up per the popular instructions and it's like a clock.  The verdict is still out on the 25FP.  Both that I've run are mildly flaky, not nearly as rock solid as the 20. 

Dig around a little here and the other forums and you'll find a ton of information on the FP's. 

Dave was referring to the Max-S series that used a softer aluminum connecting rod without bushings or oiling provisions.  In stock form they tend to get sloppy pretty fast.  The FP however has brass bushings and oiling holes.

Dave was referring to the Max-S series that used a softer aluminum connecting rod without bushings or oiling provisions.  In stock form they tend to get sloppy pretty fast.  The FP however has brass bushings and oiling holes.

Thanks Andrew. I've ahhhh.... updated my original post. The groves we use in the 35 S rod are done in a cross pattern (top and bottom of the bog end hole) rotated plus and minus about the axis 25 degrees. The slots are ~0.010 deep and ~.010 wide. We do not use them on fp rods. When it comes to fp's, the only mod I hole heartedly recommend is filling the boost port passage in the c case. We use idlebar or extended tip (ala four stroke) plugs. We've been using some of the Hanger 9 Super Plugs lately and have been impressed with them. Again I will recommend against castor in this engine. We use 18% ucon.....

Come on guys! Rob, don't bother screwing around with these things. MANY people (including me) have been there, done that. Just send the engine(s) to Randy and have him tune them. I swear, you'll save yourself a whole lot of grief and have more fun flying.

We used to buy 25FP venturi's any time we bought a new 35 or 40FP-S.  It was supposed to tame the characteristics a bit, it worked OK some of the time, but it doesn't fix the real problems with the 35/40.