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Engine basics => Engine set up tips => Topic started by: Bill Johnson on July 20, 2015, 05:33:28 PM

Title: Precision No. 218 Rigid Needle Valve
Post by: Bill Johnson on July 20, 2015, 05:33:28 PM

I acquired 2 of these NVAs new in a collection of parts and was wondering if anyone had used them before. They appear well made. OD is .125" and has a single center hole of .032". The thread pitch is greater then 44TPI (I can't seem to locate my better pitch gage). They fit an OS 20 I tried it in.

Title: Re: Precision No. 218 Rigid Needle Valve
Post by: Steve Helmick on July 23, 2015, 08:04:57 PM

There was a brand of NV Assy. way back that was quite popular. Maybe "Acme" or something like that. The earliest Fox .35's came with them as OEM equipment, FWIW. I think Fox NV Assy.'s went downhill from there.  :P Steve

Title: Re: Precision No. 218 Rigid Needle Valve
Post by: Bill Johnson on July 24, 2015, 12:11:20 PM

I just installed it in an OS Max 25 FP this morning. It's a used RC engine and I just happened to have a 6mm (.243") venturi so I threw it together, stuck it in a RingMaster I got from Ty. Fueled it up with 10/22, primed, then 10 flips. Put the glow plug driver on it and 2 flips and it's off and running.  #^

Ready to fly on the morning!

Title: Re: Precision No. 218 Rigid Needle Valve
Post by: Steve Helmick on July 24, 2015, 01:48:43 PM

"Austin" or "Austin-Craft"? I've seen a few spraybars that had the nut on the fuel inlet end...brilliant idea. I hate the nut being down in the ratchet spring. Not a fan of the whole ratchet idea, either.   R%%%% Steve

Title: Re: Precision No. 218 Rigid Needle Valve
Post by: Bill Johnson on July 25, 2015, 05:07:15 AM

These have no other markings on the package. These appear to be a general replacement NVA because neither nuts are fixed so you have the ability to adjust the orifice position. With the nut on the inlet side bottomed against the end of the threads, the orifice was about 1/8" or more off-center. After a flight or 2, I'll run some purple locktite onto the nut on the needle side.

It looks like it would be difficult  to make an NVA with the nut only on the inlet side because, as you can see on this one, there's no "nipple" to speak of because you couldn't get a nut started from that side and most spraybars are smooth in the venture open area whereas this one has threads across it. I don't see that as an issue, myself. The fuel line fits very snugly on the inlet but I did add a clamp.

Title: Re: Precision No. 218 Rigid Needle Valve
Post by: frank mccune on July 25, 2015, 06:20:04 PM

     Hi Bill:

     Where may I purchase those fuel line clamps?

                                                                                    Thanks,

                                                                                     Frank

Title: Re: Precision No. 218 Rigid Needle Valve
Post by: Bill Johnson on July 25, 2015, 08:57:18 PM

Those were marked Dubro Fuel Line Clips, Medium, Frank. 

Title: Re: Precision No. 218 Rigid Needle Valve
Post by: frank mccune on July 27, 2015, 07:03:43 AM

     Thanks Bill!

      I do not know if I "need" them but they sure look cool

                                                                           Be well my friend,

                                                                           Frank