TIA

I'm about to pick up a GMS .25 for pylon club racing but I notice I have two optons. Carb needle mount or remote rear needle mount.

Which is better?

What's the difference? (Not location)


The GMS website says the remote rear-mounted needle valve gives added engine protection. How is that?

http://www.bestrc.com/gms/index.html


One last thing, doesn't the needle valve just mix/limit the amount of fuel going through the carb? If so, how can the mixture be the same if it happens behind the engine in a remote location, then travels down a tube, in a nozzle inlet, and only then down the carb?

Doesn't sound like the mixture would be a good, or vapoous I guess you could say, than when the needle is mouted directly to the carb. No???

I guess what I'm thinking here is my car I drive everyday doesn't have fuel injectors mounted in the trunk. They're right up there in the engine.

Thanks in advance for anyones help on the subject.

[sm=spinnyeyes.gif]

wcmorrison

My Feedback: (2)

It simply means your precisous fingers are not expose to the prop when adjusting the high speed needle valve.

The needle valve adjust the flow of fuel to the carb, it does not matter if it is right on the carb or remote.

However, there are those that say the remote needle valve introduces excess vibration at its location that may cause bubbles to occur. Of that I can not comment. I have had both remote and upclose needle valves and both worked okay. I have even seen where the remote needle valve had broken off, but was still functional in the fuel line. It was just hanging out there but still worked.

Good luck.

Cheers,

Chip

XJet

The GMS remote needle is prone to air leaks where the needle carrier screws into the body. I usually fix this by using a little red silicone sealant (the stuff designed for automotive gasket purposes).

Apart from that they're trouble-free.

Flyboy Dave

My Feedback: (21)

I always prefer the carb with the needle in it, not the remote style.

FBD.

Sport_Pilot

The bubbles are often just because of the drop in pressure past the needle, not a problem unless they collect in one point instead of moving on with the fuel. Usually the fuel vapors dissapear as the fuel moves down the line. But sometimes the valve does leak air, people see it, when they couldn't notice the same thing on a carb mounted needle valve.

itsme

Hi there,

Whether your needle valve is right at the carb, or remote, it will still work properly. There are a few reasons how we know this. The first is that engine manufacturers wouldn't still be selling remote needles if they didn't work and the second is that the atomisation of the fuel still occurs in the carburettor regardless of where the needle is. The jet where the fuel enters the engine is still in the same place and this is where the fuel/air mixture is created. The needle merely regulates the quantity of fuel that gets to this jet.

Regards
Warren

ClassicFI

Just a thought.

Could you possibly mount the bracket to another surface, like the firewall, with the needle valve's head sticking outside of the body? OS says in the 91 manual something like 5 inches away.


Thanks,
Dan

blw

My Feedback: (3)

Dan,

Yes, people do that often. Some people do that after a crash where the remote needle valve bracket is broken off of the backplate, but otherwise okay. Or, if using another remote from another brand/size engine. I've seen this done with the OS .91 FX because of problems.

skiman762

I wonder why OS started moving them back to the carb they don't makes changes without a good reason
I always like them there anyway 2 less fuel line conections to deal with

Ed_Moorman

My Feedback: (1)

I've never had any problems with the rear GMS needles leaking. As a matter of fact, I have two OS .25FXs on a delta twin, both with GMS .25 rear needles and they still run like OSs. I saw the worthless (in my opinion), cast-on extension off the OS backplate and install the GMS rear needle assembly. I think it's one of the best rear needles around.

My GMS engines (2-.47, 4-.32) all have the front needles. Since I have been tuning engines since 1950, I have learned to keep my fingers out of the prop nearly all the time.

proptop

My Feedback: (8)

I've never had any leaking issues with the GMS remote NV's, maybe because I always check the tightness of all the nipples first? I have found a few that weren't very tight and probably would have leaked.

I prefer the NV right on the carb though...call me old fashioned

jeffie8696

I suffered a really bad set of cut fingers (needed stiches) once from my .46 running a razor sharp APC prop[:@]. I am very very very nervous and cautious near any needle valve. I have changed my ways that's for certain. I was having a really bad day. [sm=lol.gif] I have both and noticed that MAYBE the fuel adjustments are a little quicker to respond with the needle on the carb, but I am willing to live with that.

P.S. I just started and broke in my GMS .32 today. I have a new favorite engine now!!!!!!!! I will be selling my LA46s. I think this engine is powerful enough to drag around any plane those cheap LA's can. Just my opinion no bashing please.