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Engine basics => Engine set up tips => Topic started by: Jim Oliver on February 23, 2007, 03:23:32 PM

Title: Question about Needle valve position for CLPA models
Post by: Jim Oliver on February 23, 2007, 03:23:32 PM

What is the best orientation for the Needle Valve for CLPA models with upright/inverted engines--should the needle valve exit the nose to the outside of the circle or to the inside of the circle? 

Does it really make any difference to the engine?

Thanks,
Jim

Title: Re: Question about Needle valve position for CLPA models
Post by: Bill Little on February 23, 2007, 06:34:11 PM

Hi Jim,

I think it sure makes plumbing the fuel line from the tank to the NVA easier (with a metal tank) if the needle comes out to the inside of the circle.  Straight shot from the tank feed line to the inlet nipple on the NVA.

Bill <><

Title: Re: Question about Needle valve position for CLPA models
Post by: RandySmith on February 23, 2007, 09:40:37 PM

Quote from: Jim Oliver on February 23, 2007, 03:23:32 PM

What is the best orientation for the Needle Valve for CLPA models with upright/inverted engines--should the needle valve exit the nose to the outside of the circle or to the inside of the circle? 

Does it really make any difference to the engine?

Thanks,
Jim

Hi Jim

Many times  it will make a big differance, it will be  hard to needle the exact setting you want if you put the fuel pickup side on the inboard instead of the outboard, many engines  will go lean when launched, some motors  act differant, it is best  to use the fuel pickup side  on the outboard

Randy

Title: Re: Question about Needle valve position for CLPA models
Post by: Jim Oliver on February 24, 2007, 07:15:38 AM

Thanks for the info--as we used to say "Wilco".

Jim

Title: Re: Question about Needle valve position for CLPA models
Post by: Jim Thomerson on February 24, 2007, 10:35:28 AM

In agreement on the NVA.  A little off subject! I ran a K&B 4011 inverted with the case turned so the exhaust was outboard,  Ran the muffler line through the fuselage and out the inside to get to the uniflow vent.  Looked sort of strange, but worked fine.

Title: Re: Question about Needle valve position for CLPA models
Post by: L0U CRANE on February 25, 2007, 01:41:55 AM

As an exception - a special case - to the general rule that the 'more direct' fuel line connection is the best, I had a Sterling YAK-9/Fox35 that needled better with an added loop of fuel line between tank and engine...

Short, direct fuel connection didn't compare. NVA was stock Fox, so fuel jet position ideas were neutralized - spraybar oriented so that NEITHER jet was visible from outside the engine. It may be that the "line loss" of the extra length 'broadened' the needle valve response - required a bit more "open" than a shorter fuel path - but, by golly, it worked! This may be another tuning item we could look at... if nothing else helps.

Title: Re: Question about Needle valve position for CLPA models
Post by: Bob Reeves on February 25, 2007, 08:03:45 AM

You can always find an exception.. Built a stunt ship using an Oriental wing several years ago and when I made the cowl I didn't realize the needle was turned around in the Max 35S I was planning on using so went ahead and drilled the needle hole and everything was cool till after I had it finished and started installing the tank. I just routed the fuel line around behind the engine and went on. Someone else now owns it but that airplane is still flying with a Brodak 40 and needle protruding from the wrong side. The 35s ran great and so does the Brodak 40.