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Engine basics => Engine set up tips => Topic started by: Allen Eshleman on December 07, 2015, 04:55:14 AM
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I just scored an OS FP 25 R/C on the bay. Are an nva and a venturi enough to to the conversion to C/L? I see they are available from Tower. Should I fly it awhile with the carburetor wired open to see if I like it? Not sure whether it's ABN or the older version. I think it's the older version.
What fuel should I use?
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If you do as I have done and still do I just locked the carb in the full open position. As for fuel, I've been using the regular r/c fuel, 10% nitro and whatever oil was in it .... 18%, 20%, whatever ;). Heck, I've gotten well over 50 flights on mine and it's still running on the plug that it came with. I figure I'll smash it in a crash before I can fry it in-flight ;D
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Allen,
you may want to spend a few minutes on the search feature here, there are quite a few posts dealing with the FP 20 and 25 that would be very helpfull for you
part of the answer will depend on what you are trying to accomplish,, sport flying or stunt?
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part of the answer will depend on what you are trying to accomplish,, sport flying or stunt?
And if you still crash a lot. It's easy to relocate the FP remote needle so it won't get hurt in all but the worst crashes. I started flying with a 20FP that had the stock venturi and a remote needle -- I could plug that engine six inches deep into the dirt and not touch the needle valve.
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And if you still crash a lot. It's easy to relocate the FP remote needle so it won't get hurt in all but the worst crashes. I started flying with a 20FP that had the stock venturi and a remote needle -- I could plug that engine six inches deep into the dirt and not touch the needle valve.
And it works very well, there's no reason at all to change it. The FP rear needles were easier to move. The LA rear needles tend to break the backplate in half. It should be possible to rotate it 90 degrees, too, at which point it will also be indestructible. But I haven't tried that in flight yet, and as always, I wouldn't want to start anyone down the engine modification path, which is more of a psychological issue. If anyone asks me about engine problems they are having, the first question will be "are you using al the stock parts".
The metal FP rear needle is actually the core of an RC carburetor. They used to sell it separately as part of a rear needle kit. It worked very well to put a rear needle on a Fox 35, too.
BTW, the plastic backplate on the LA is fine as it is, but *do not overtighten it*. If it is over-tightened, it will crack where the screws go through and then leak. If that happens, take the backplate off, clean it with acetone and alcohol until it is perfectly dry, then run a small (~1/16" diameter) bead of silicone sealant around the thing right at the corner, then put it back on the engine and *snug* up the screws. That hasn't happened to mine because I saw other people do that and end up with cracks.
Brett
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And it works very well, there's no reason at all to change it.
The only reason I could see to change it would be if you want to change to a venturi and can't find a plain spraybar without a needle. (Tower sells needle valves and venturis to fit the engine, but I looked just now and couldn't find a plain spraybar. If you have a lathe and want to play, a spraybar is one of the easiest projects there is, but it does require a lathe.)
If I were building a plane for someone who crashes a lot, I'd be tempted to get a needle valve assembly from Tower, take the needle out of the spraybar, and solder a plug into the hole, and use the remote needle.
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After having read this post and others, I think I will run it for awhile with the carburetor. I do want to use it for stunt in place of my burping foxes and McCoy 35's. I will start using it on a Trixie. I also have an old Cosmic Wind that is very heavy. I have a good Doodle Streak but will continue for now, to fly it with a Fox 35 with the anti-burp stick in it. It really runs. It looks like there are plenty of venturis and NVA's at Tower. I have been bursting to try out an FP or LA 25. I actually don't have this one yet. Waiting for the mail.
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This one has the metal back plate and the needle valve in the carburetor in front. It has the bypass hump so it must not be ABN.
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I crash something about three times a summer.
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It appears to me as thought the needle on Tower Hobby has the spraybar with it. LXCR49 O.S. Needle Assembly 20-25FP-S
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This one has the metal back plate and the needle valve in the carburetor in front. It has the bypass hump so it must not be ABN.
look here to tell the difference conclusivly
http://stunthanger.com/smf/engine-set-up-tips/how-to-tell-the-difference-between-steel-and-abc-fp-engines/