Repositioning of needle valve ASP 46

I have repositioned the needle valve in my ASP 46 engine which was originally a remote valve mounted with a bracket at the backplate to the carburretor directly .

The engines starts easily but will not accelerate beyond 1/3rd throttle position and also cuts as soon as the glow plug heater is removed.

Please advise.

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Repositioning of needle valve ASP 46

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Mar 12, 2010
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moved your question to a new thread
by: Matt

Hi Phillip,

Since this question is unrelated to engine tuning
I have moved your new question here.

Mar 11, 2010
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Matching Receivers
by: Philip

Dear Matt,
Greetings, Thank you once again for the informative discussions and advice seen on your page.
I am using a Futaba 6EXHP TX with a R136 HP receiver PCM 1024 Hi band , RX 50 with 72.790 frequency. The TX can be programmed for 6 models. Can I use a Futaba R148 DP in the same range, in a second model since the original R136 HP is no longer available.
Regards, Philip.

Aug 23, 2009
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ASP 46
by: Philip

Matt,
Just a note to let you know that I was able to finally fly the Sig Kadet with the ASP 46 that I had talked to you about. It was a maiden flight and it went off well and the engine responded well. Thank you for your suggestions and advice.
Regards, Philip.

Aug 08, 2009
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Good luck this weekend
by: Matt

Sorry for the delay in response. Been a busy couple of days.

Sounds like you are making progress by leaning it out. Sounds like maybe you need to lean it more.

By moving the position of the valve it may need to be set at a different position than it was previously. Just because it only needed 3/4 of a turn when it was remotely mounted doesn't necessarily mean that it will need the same amount at its new location.

By moving it you have changed the physics a little but. There is more tubing between the tank and the valve and I would imagine the elevation is different.

It takes a fine balance to keep a glow engine running because it doesn't have a pump, the engine itself must pull the fuel from the tank. So it doesn't take much to disturb that delicate balance.

I would just forget about how it was set before. The engine doesn't have to be running full throttle to perform the pinch test.

Run it up to just under the point where it usually dies and pinch the tubing. If its too rich the RPMs will rise. If it quits right away without increasing it is probably too lean.

It is also possible the low end adjustment is off. The low end is very important for transitioning from idle to full throttle.

Good luck this weekend. Hopefully you will be flying with some people who can help you get'er straightened out.

Matt

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Aug 08, 2009
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Submitted by: Matt

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Sorry for the delay in response. Been a busy couple of days. Sounds like you are making progress by leaning it out. Sounds like maybe you need to lean it more. By moving the position of the valve it may need to be set at a different position than it was previously. Just because it only needed 3/4 of a turn when it was remotely mounted doesn't necessarily mean that it will need the same amount at its new location. By moving it you have changed the physics a little but. There is more tubing between the tank and the valve and I would imagine the elevation is different. It takes a fine balance to keep a glow engine running because it doesn't have a pump, the engine itself must pull the fuel from the tank. So it doesn't take much to disturb that delicate balance. I would just forget about how it was set before. The engine doesn't have to be running full throttle to perform the pinch test. Run it up to just under the point where it usually dies and pinch the tubing. If its too rich the RPMs will rise. If it quits right away without increasing it is probably too lean. It is also possible the low end adjustment is off. The low end is very important for transitioning from idle to full throttle. Good luck this weekend. Hopefully you will be flying with some people who can help you get'er straightened out. Matt

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Aug 08, 2009
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answers to questions
by: Philip

Matt,

Yes the needle has been moved from the original position. I have now achieved a fairly good idle at about 2 turns of the low speed valve.

Unable to do the pinch test yet since i have not been able to get full throttle.

The engine now runs without the ignitor since I
have leaned it out more. However still cannot achieve any more than 1/3rd throttle.

Yes the bracket broke in a crash and I was unable to substitute a satisfactory bracket.

The needle looks ok, but has always needed only about 3/4 turn to achieve max power.

Hoping to run this engine on a new Sig Kadet Model this weekend if the engine running can be sorted out.

Regards, Philip.

Aug 08, 2009
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more questions...
by: Matt

Have you tried to adjust the needle at all since you moved it?

Did you do the pinch test to adjust the high end?

What broke the bracket? Did you crash? Have you removed the needle completely to make sure it's not damaged or bent?

Matt

Aug 08, 2009
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Thank you for the response
by: Philip

Matt,
Thank you for the response.
Yes the engine used to run fairly well before the change.

The repositioning was done since the bracket was damaged.

Without the ignitor the engine does not run. The throttle response with the ignitor was poor.

Aug 06, 2009
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can you clarify?
by: Matt

Hello,

Did the engine run fine before you moved the needle?

When the engine runs fine, then dies when the glow ignitor is removed from the plug, this means that it is probably running too rich.

Will the engine run at idle speed without the glow ignitor? Or will it not run at all without the glow ignitor?

Or does it run fine without the glow ignitor at idle speed, but will only run above 1/3 throttle with the ignitor attached?