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3.5 cc diesel needs needle valve

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Wanted 3.5 cc diesel needs needle valve

Post  kendias on Wed Sep 27, 2017 6:25 pm

Looking for a needle valve for the above engine
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Wanted Re: 3.5 cc diesel needs needle valve

Post  pkrankow on Wed Sep 27, 2017 8:29 pm

There have been a very large number of 3.5cc diesel engines manufactured by many different companies over the years.

With nothing else to go on besides displacement I would point you to a OS needle
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXCR49&P=ML

I would also recommend you measure the existing parts, or the spraybar hole so you can determine if this is a reasonable choice. There are many other needle valves,
PAW
Fox (although harder to get now)
and many many others. There are dimension differences between different brands, which will affect fit and choke area.

Phil
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Wanted Re: 3.5 cc diesel needs needle valve

Post  kendias on Thu Sep 28, 2017 3:36 pm

Thanks Phil.
Here is a pic of my engine missing the needle valve. Not sure if that is all I need.
Please let me know.

Ken
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Wanted Re: 3.5 cc diesel needs needle valve

Post  kendias on Thu Sep 28, 2017 3:44 pm

Sorry, was not able to load the image - don't know how!
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Wanted Re: 3.5 cc diesel needs needle valve

Post  pkrankow on Thu Sep 28, 2017 7:14 pm

kendias wrote:Sorry, was not able to load the image - don't know how!
(in my best pirate accent)
'Tis the CURSE of being a new member.

(lol)

There is a time limit on when you are allowed full posting access. It is something like 30 days. You can email the images to me and I can post them here.

pkrankow (at) yahoo.com

Put something about Cox Engine Forum in the subject, and tell me about the pictures so I can cut and paste with the images.

Phil
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Wanted Re: 3.5 cc diesel needs needle valve

Post  Admin on Fri Sep 29, 2017 2:02 am

pkrankow wrote:
kendias wrote:Sorry, was not able to load the image - don't know how!
(in my best pirate accent)
'Tis the CURSE of being a new member.  

(lol)

There is a time limit on when you are allowed full posting access.  It is something like 30 days.  You can email the images to me and I can post them here.

pkrankow (at) yahoo.com

Put something about Cox Engine Forum in the subject, and tell me about the pictures so I can cut and paste with the images.

Phil

Just 7 days, not 30. It keeps the spammers from getting their way.

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Wanted Re: 3.5 cc diesel needs needle valve

Post  pkrankow on Fri Sep 29, 2017 10:06 am

https://i.servimg.com/u/f11/17/84/87/39/20170910.jpg



Thanks Phil. This pertains to my posts and your replies on the Cox engine forum.
This is a pic of the engine showing where the needle valve was (once upon a time!). Not sure if the needle valve is all I require as I will have to mount it and not sure how. It is an ED Diesel I believe.

Regards,

Ken

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Wanted Re: 3.5 cc diesel needs needle valve

Post  Surfer_kris on Fri Sep 29, 2017 11:12 am

It looks like you need the whole spraybar and needle valve assembly.

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Wanted Re: 3.5 cc diesel needs needle valve

Post  pkrankow on Fri Sep 29, 2017 12:19 pm

Is that a cross hole through the intake assembly? I am having a hard time telling.

Phil
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Wanted Re: 3.5 cc diesel needs needle valve

Post  Surfer_kris on Fri Sep 29, 2017 3:33 pm

It looks to me like there is a cross hole, so it is mainly a matter of finding a spraybar with the right diameter, I guess.
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Wanted Re: 3.5 cc diesel needs needle valve

Post  kendias on Fri Sep 29, 2017 8:33 pm

Thanks!
Not sure where to get the spray bar - any suggestions welcome. Also what dimensions i.e. take measurements of the cross-hole? Please suggest.
Will try Phil's link for the needle valve.


Last edited by kendias on Fri Sep 29, 2017 8:35 pm; edited 1 time in total (Reason for editing : more detail)
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Wanted Re: 3.5 cc diesel needs needle valve

Post  Surfer_kris on Sat Sep 30, 2017 1:47 am

You will need to know the diameter and the length of the hole through the venturi.
I don't have any ED diesels myself, but here is was the original needle assembly might have looked like;

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Wanted Re: 3.5 cc diesel needs needle valve

Post  KariFS on Sat Sep 30, 2017 2:02 am

PAW (Progress Aero Works) sells spare needle valve assemblies for their own diesels, and the prices are reasonable (£5.50). Maybe one of those could be adaptable?

Their website:

http://www.eifflaender.com/index.htm

If you measure the hole and diameter as Kris suggests, the PAW people may be able to help you.
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Wanted Re: 3.5 cc diesel needs needle valve

Post  Surfer_kris on Sat Sep 30, 2017 2:30 am

This later version seems to match the engine better;
(for a bit of history look here; http://www.modelenginenews.org/cardfile/ed_story.html)

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Wanted Re: 3.5 cc diesel needs needle valve

Post  Oldenginerod on Sat Sep 30, 2017 5:20 am

Surfer_kris wrote:This later version seems to match the engine better;
(for a bit of history look here; http://www.modelenginenews.org/cardfile/ed_story.html)


The needle in this picture looks very similar to the Testors needles used in the Red Heads and Series 21 engines.  Still available from MECOA.
https://www.mecoa.biz/shopexd.asp?id=1450
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Wanted Re: 3.5 cc diesel needs needle valve

Post  pkrankow on Sat Sep 30, 2017 10:22 am

The required dimensions are the diameter of the hole and the length of the hole from flat to flat. The length is easier to get, just measure it with a caliper or micrometer. The diameter is easiest to get with the butt end of drill bits, unless you have an inside caliper and are good at using it.

The measurements of various manufacturers NVA are not necessarily published by the manufacturer which will make this a little more difficult. Length can be worked with by shimming with small washers on either side if necessary. Diameter less so, but can be worked with.

Phil
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Wanted Re: 3.5 cc diesel needs needle valve

Post  roddie on Sat Sep 30, 2017 12:00 pm

We have a member here; "ian1954" who lives in England. He is a model engine collector.. and machinist. He's also very knowledgeable with diesels. He's usually an active-poster.. but has taken some time-out recently due to relocating.. and temporary sub-standard internet-access. Yours is a topic that he'd surely be interested in.. and would likely offer his recommendations for a fix. Unless you're in a hurry to restore the engine to running-condition; I'd personally wait a little while for some more information.

As mentioned; even if you can't find the exact replacement needle valve assembly, you can surely source one that can be adapted to work. There are other considerations for a proper installation.. such as the jets' (fuel spray-hole) orientation in relation to the air-flow through the venturi. You'll want that to be optimized for the best atomization of the fuel-mixture. Try to find info/literature on that in the meantime.

Good luck! Thumbs Up







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Wanted Re: 3.5 cc diesel needs needle valve

Post  kendias on Sat Sep 30, 2017 5:43 pm

Thanks.
Only option then is to order the NVA and spray bar and hope for the best since the mfr's don't give dimensions?
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Wanted Re: 3.5 cc diesel needs needle valve

Post  kendias on Sat Sep 30, 2017 5:51 pm



I guess I may have to bite the bullet and order this from MECOA: Item #87-0201 - or maybe a member of this forum can help me - question being will this part work on my 3.5 cc engine?


Last edited by kendias on Sun Oct 01, 2017 8:51 am; edited 2 times in total (Reason for editing : correction)
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Wanted Re: 3.5 cc diesel needs needle valve

Post  KariFS on Sun Oct 01, 2017 9:48 am

I still suggest that you measure the diameter and the length of the spraybar hole of your engine. Then all of us can eyeball our engines and maybe find an assembly that would fit, and maybe some of those suitable assemblies would be more readily available than the ED one you are looking for. I have a PAW diesel, a MARZ and one Chinese engine that may be close (or maybe not), but at least those spraybars are less hard to find.

Just my Two Cents Smile
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Wanted Re: 3.5 cc diesel needs needle valve

Post  roddie on Sun Oct 01, 2017 11:22 am

The Mecoa replacement NVA your considering is made to fit the McCoy series 21 engines of various displacements.. but are in the size-range of your engine. The Mecoa part is claimed to also fit the earlier McCoy engines.. so I checked one of my McCoy .19 "red-head" engines' venturi to find the NVA hole to be .161"... so your engines' venturi would need through-holes of that size. If they're smaller; DON'T drill them out until you have the replacement-part in hand to measure it.

The venturi "width" on my engine is .482".. and the Mecoa NVA is sized to orient the "jet" (spray-hole) in the center of the venturi-throat. This is an important consideration. The venturi on your engine is likely narrower in width.. (gaging from the supplied photos) which would require "shimming" the replacement-part to orient the fuel-jet on-center.

The .161" venturi through-hole size would be bored by using a #20 drill-bit. Obtain that size drill.. and you'll be able to make your own precision shims from various thicknesses of material. These would be installed on the NV body; up-against the hex on the fuel-nipple side. Making shims is as easy as drilling a few holes near the edge of your shim-material.. then cutting the pieces out with shears. Cut the corners "round" so there's no sharp edges. You're essentially making your own "flat-washers". Thin-sheet plastic, aluminum or tin should work equally well. You may only need a couple of shims to center the fuel-jet.

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Wanted Needle valve

Post  kendias on Mon Oct 02, 2017 8:18 pm

KariFS wrote:I still suggest that you measure the diameter and the length of the spraybar hole of your engine. Then all of us can eyeball our engines and maybe find an assembly that would fit, and maybe some of those suitable assemblies would be more readily available than the ED one you are looking for. I have a PAW diesel, a MARZ and one Chinese engine that may be close (or maybe not), but at least those spraybars are less hard to find.

Just my Two Cents Smile
Thanks.
The dia is approx. 1/8" and length of the s.b. hole is approx 7/16". Let me know how this fits in.
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Wanted Re: 3.5 cc diesel needs needle valve

Post  pkrankow on Mon Oct 02, 2017 9:03 pm

...with horrible precision.
1/8 is 0.125
3/16 is 0.1875

7/16 is 0.4375

Assuming you are using a ruler or tape measure then most all NVA will be in the ballpark.

You really need a number/letter drill index and a micrometer caliper for doing this frequently. The caliper will be "adequate" if this is a one off event.

An inexpensive set of vernier calipers in plastic will set you back less than $10, and a cheap set of metal calipers less than $30 and will be adequate for the task at hand. You will also want a metric set so I recommend the plastic vernier calipers as an entry point to precision measurement. A set of digital calipers that can measure both metric and inch will be a little more, but a cheap set will be less than $50. The micrometer that looks like a C-clamp is only capable of outside measurements, but is generally more accurate than a caliper micrometer, at least in the lower price points.

https://www.amazon.com/s/?ie=UTF8&keywords=metric+vernier+caliper&tag=googhydr-20&index=aps&hvadid=174224604196&hvpos=1t1&hvnetw=g&hvrand=3889277574941187717&hvpone=&hvptwo=&hvqmt=e&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9014991&hvtargid=kwd-11597361565&ref=pd_sl_3b7xzixdsl_e

0.001 is plenty accurate for most applications, even with these little engines, until you are interested in making parts.

Phil
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Wanted Re: 3.5 cc diesel needs needle valve

Post  kendias on Wed Oct 04, 2017 3:20 pm

Thanks.
Measured with a Vernier:
Hole dia = .130"
Length across flats = 0.45"
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Wanted Re: 3.5 cc diesel needs needle valve

Post  roddie on Wed Oct 04, 2017 4:40 pm

kendias wrote:Thanks.
Measured with a Vernier:
Hole dia = .130"
Length across flats = 0.45"

I measured a 2nd McCoy .19 Red Head engines' cross-hole in its' venturi.. and it measures .157". A standard fractional 5/32" drill is .1562". The Mecoa NVA is likely 5/32" diameter. I used a #22 drill (.157") to gage the cross-hole in the 2nd engine. This measurement makes more sense than the 1st engine I measured.. although it was only .004" larger.

The venturi's outside width on the 2nd engine measured .489" which is an approx. .040" wider than your 0.450" measurement. Fitting the Mecoa NVA would require a .020" shim on the fuel-nipple side, to properly center the fuel-jet.

Again; DOUBLE-CHECK the Mecoa part BEFORE you do any drilling. The holes MUST be drilled square to each other. Unless you have experience in machine-work/holding-fixtures and access to a drill-press; it would be well-worth having a machine-shop do the work. If you explore that option; bring the NVA with you for a machinist to also measure. It's a 10 minute job to set-up.. and they may not even charge you.








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