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how do you get to your needles? - 11/20/2012 8:10 AM   
3136


 

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From: Victoria, AUSTRALIA
Status: offline 		Hi guys,
I have always had trouble tweaking my needles when they are in a cowled plane, I saw a post recently how someone used brass pipes to direct the screwdriver to the needles.
That looked good, when I tried it, I didn't always get a good line up with the screwdriver, so I thought what else could work.
Then thinking about glow set ups, I adapted that principle, simply put some glow fuel tube over the needle then stuck some inner sullivan flex rod in the other end.
After break in and everything is settled the rods can simply be pulled out.
There must be lots of ways, let me know if you have an easier idea.
I wish I thought of this before making those two big dirty holes.

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RE: how do you get to your needles? - 11/20/2012 12:10 PM   
earlwb


 

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Status: offline 		My engines all have some sort of a Walbro carb on them. So I just use a Walbro Carb needle adjusting tool. It looks like a socket driver tool, but the tip is splined to fit on the outside of a needle.So it is easy to get a grip on the needles to tweak them as needed. The splines work much better for getting a grip on the needles as you aren't trying to get a screwdriver tip into the slot on the needle.

In the past I used a screwdrvier with a short tube epoxied over the tip. The tube served as a guide for the tip to get it onto the needle so I could adjust the needle.

For those "new" carbs with the "D" shaped needles, I use a similar tool, where I took a rod and glued a tube over the tip that was shaped to match the "D" needle tip shape.

For a cowed in engine, I used some soda drinking straws cut to length to fit over the needles as a guide to help me get the tool down to the needles. The tool mentioned above could easiiy fit the splines on the needle head making it easy to adjust the needles. I used a small dab of silicon adhesive to hold the straws in place. As if you had to remove the cowl, it would likely tear up the straws anyway. So I wanted it to be easy to replace. Our local convenience stores tend to sell extra large soft drinks and have extra large super sized straws to match too. So it is easy to get more sraws as needed.





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RE: how do you get to your needles? - 11/20/2012 1:53 PM   
dant-RCU



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Status: online 		You have to tweak the needles on a gas engine? Really?

On those very RARE occasions when I have to tweak mine I just remove the cowl.

Dan


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RE: how do you get to your needles? - 11/20/2012 2:28 PM   
ahicks


 

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Status: offline 		One of the problems I face is the fact the needles are so close together? If I slip a short length of snug fitting brass tube over each like I normally do, they're rubbing on each other? No room for fuel line on mine I don't think (20-30cc)?

earlwb - you've given me an idea I think! If you had a section of soda straw that fit snug in the hole in the cowl, you could slip that in when you wanted to adjust, adjust away with your screwdriver that was long and small enough to fit down through it, then remove it prior to flying? The snug hole would hold the straw in place against the prop blast, and removing it when done adjusting would avoid trying to figure out how to get the cowl on and off without disturbing it? Thanks! Thinkin I'm going to give that a try!

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RE: how do you get to your needles? - 11/20/2012 3:33 PM   
daveopam



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Status: offline 		A straw from your local fast food joint works pretty well. It will need some sort of support on the other end, but it can be slid over each of the needles.

David

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RE: how do you get to your needles? - 11/20/2012 5:56 PM   
earlwb


 

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quote:

ORIGINAL: dant-RCU

You have to tweak the needles on a gas engine? Really?

On those very RARE occasions when I have to tweak mine I just remove the cowl.

Dan


Yeah usually twice a year I need to tweak it a little bit, the weather change from winter to spring, to summer to fall to winter. Usually just a idle speed adjustment is needed, but sometimes a needle adjustment is needed if the ambient temperatures change a lot. But usually once the needles are set I don't need to touch them.  But sometimes during break in with a new engine, I have to tweak them some more as the plane flying continues and the engine beds in.






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RE: how do you get to your needles? - 11/20/2012 8:00 PM   
pilotpete2



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Status: offline 		I simply silver solder heads cut off of Allen cap screws to the top of the needles. A head from a 4/40 for the LS needle and a 6/32 for the HS needle. I can never remember the correct fractional size, so the appropriate ball drivers are marked clearly with an L and H. I never accidentally wind up turning the wrong needle
Pete


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RE: how do you get to your needles? - 11/20/2012 8:15 PM   
3136


 

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From: Victoria, AUSTRALIA
Status: offline 		Some great ideas there fellas, Earl I didn't know about that walbro tool.


quote:

ORIGINAL: dant-RCU

You have to tweak the needles on a gas engine? Really?

On those very RARE occasions when I have to tweak mine I just remove the cowl.

Dan

Read the entire post. You must have missed the part where I said "After break in and everything is settled the rods can simply be pulled out."

They are a bit unsightly to leave in forever.

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RE: how do you get to your needles? - 11/21/2012 10:50 PM   
john josey


 

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quote:

ORIGINAL: 3136

Hi guys,
I have always had trouble tweaking my needles when they are in a cowled plane, I saw a post recently how someone used brass pipes to direct the screwdriver to the needles.
That looked good, when I tried it, I didn't always get a good line up with the screwdriver, so I thought what else could work.
Then thinking about glow set ups, I adapted that principle, simply put some glow fuel tube over the needle then stuck some inner sullivan flex rod in the other end.
After break in and everything is settled the rods can simply be pulled out.
There must be lots of ways, let me know if you have an easier idea.
I wish I thought of this before making those two big dirty holes.


I made this from brass tube, rod and strip. It took about 20 minutes, but you do still need a hole in the cowl the size of the brass tube.



Fits snug over the needles





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RE: how do you get to your needles? - 11/22/2012 2:48 AM   
dubs1946


 

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From: sydney, AUSTRALIA
Status: offline 		This is an idea that worked for me, it was another club members brain wave and i made the special screw drivers etc
The problem i have is adjusting the needles with the engine running, to keep stopping the engine and adjusting restarting etc is a problem.
I wanted a 100% certain lock onto the needles but with the engine cranking 6000 rpm its very difficult to get a positive lock even with the funny type screw drivers that i had made before some of those you can see in this thread but none was a certain 100% solid lock on.
The problem is you cannot feel or see the needles and most of the time i was not sure if i had moved the needle or not and it sometimes only needs a small tweak.
I silver soldered a small Tommy bar in the groove of the needle the Tommy bar stood out both sides by a small amount and then picked a brass tube that would fit over the needle and cut a groove in it as you can see in the shot, you can have the cut as deep as you like.
That tube with the cut would then go over the needle and the groove would slide down the tommy bar and the tube would go in to the depth you have cut the groove and with the engine bouncing about at 6000rpm you will still have a positive lock on the needle.

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RE: how do you get to your needles? - 11/26/2012 9:49 PM   
bgw45


 

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Status: offline 		I don't tweak. I do make some seasonal adjustments. Here is the method I use. I take two different lengths of red flexible servo rod. I put about an inch of red rod and cover it with about 3/4" of heat sink. I slide the heat sink over the rod and down on the first turn of low speed needle spring. Heat that to shrink to the spring needle and hollow servo rod ( like goldenrod ).

Since the high speed needle is behind ( further into the cowl ) the length of rod is about 1 3/4" staggering so I can see both easily from openings in the front of the cowl. This allows me to identify the correct needle easily. I use the same heat shrink method holding these guide tubes to the carb needles and it works ok. It makes getting a small/long screwdriver in position so much easier.

If you are heavy handed, don't bother as you will knock these things you just made off the carb. I do have this set-up on several airframes and just haven't come up with anything better.

Good Luck!

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RE: how do you get to your needles? - 11/27/2012 3:42 AM   
av8tor1977



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Status: offline 		Well, everyone has their favorite methods.... Here's mine. Takes a few minutes to do, but works great. With the modified high speed needle valve, I can actually just make the high speed needle adjustments by hand on the test stand; just like a glow engine. Once it is in the airplane, I use a small hole I make in the cowl with a rubber grommet around it to access the high speed needle valve. (The low speed usually isn't as much of a problem because there is less vibration, etc. going on while adjusting the low speed needle, plus usually once it is close you can just stop the engine, give it a tweak and try again.)

Just a piece of brass tube with a piece of pushrod soldered in crossways, then soldered to the high speed needle. Sacrifice an old screwdriver for the tool, and you're set!

The pics tell the story.....

AV8TOR

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RE: how do you get to your needles? - 11/27/2012 3:01 PM   
ahicks


 

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Status: offline 		Geezz, ideas like this are why I'm so addicted to this place. Thanks AV8TOR, I'm going to try that right away.

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RE: how do you get to your needles? - 11/27/2012 5:30 PM   
av8tor1977



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Status: offline 		You're welcome. I do this to every gas engine I have. It is really nice to be able to adjust the high speed needle on the test stand without using a screw driver; just doing it by hand. When adjusting on the plane, I insert the modified screwdriver through the hole in the cowl and engage the high speed needle before I even start the engine. Then I start it up, make my fine tuning adjustment, and I'm done.

AV8TOR

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RE: how do you get to your needles? - 11/27/2012 6:38 PM  1 votes
ahicks


 

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From: Waterford, MI, USA
Status: offline 		Until now, my problem has been tuning/adjusting with the cowl in place. This mod should pretty much take care of that....

I've been shutting the engine down between "tweaks". What a PIA....

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