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Old Aug 15, 2012, 02:02 PM
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I think Turk was suggesting moving the pick up a bit in both directions and checking RPM . Setting timing just a bit late (retard) of where peak is achieved .
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Old Aug 15, 2012, 02:13 PM
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Ahh, yes. That is a good idea. I remember him tweaking the timing a little and getting some more RPMs out of his engine.
Thanks
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Old Aug 15, 2012, 08:56 PM
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talent!
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Old Aug 15, 2012, 09:00 PM
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brace's Avatar
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Right so Michael we need an adaptor plate, a walbro carb and a spacer for the prop shaft. What can NGH do in that regard?
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Old Aug 16, 2012, 12:56 AM
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I hope that's not the fix. I mean kudos to Earls' patience and knowledge on mechanics of the problem but where would I find a .40 size plane with a cowl big enough to fit this monstrosity?

I could create a drive shaft and fit the engine in the fuselage.
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Old Aug 16, 2012, 01:21 AM
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Maybe not the fix but a great alternative if people wish to go that way
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Old Aug 16, 2012, 01:51 AM
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Quote:
Originally Posted by Gary Cee View Post
I think Turk was suggesting moving the pick up a bit in both directions and checking RPM . Setting timing just a bit late (retard) of where peak is achieved .
Most Exactly, thanks.
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Old Aug 16, 2012, 09:01 AM
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Quote:
Originally Posted by gravityking View Post
I hope that's not the fix. I mean kudos to Earls' patience and knowledge on mechanics of the problem but where would I find a .40 size plane with a cowl big enough to fit this monstrosity?

I could create a drive shaft and fit the engine in the fuselage.
Yeah it might be a problem with some cowled airplane setups. I have used the Fox shaft extenders with Fox engines a lot, as the Fox engines have short front ends on them from their control line heritage. I could set the prop 3/4 inch farther out as needed in some installations as there are 1/2 and 3/4 inch extenders. But one doesn't really need the intake stack. The other issue might be engine overheating in a tightly cowled scale plane. Something I haven't tackled or studied. The gas engines tend to run more hot irrespective of how they are mounted, etc.

A Great Planes Cessna Skylane is one example where it looks like one would have room for it. A plane with a radial cowl is another example.

Actually folks are getting the OEM carb to work well for them. Mine might have been defective in some subtle way. A cowled setup might be better in this case too. Using a pitot tube routed inside the fuselage might have solved some problems too.

I wish NGH had carb rebuild kits available, as it is easy to damage a diaphragm in some situations. That was one driving reason behind going with a Walbro carb. If I had problems I could put in a new diaphragm from a locally available rebuild kit. I did rupture a rubber diaphragm on the carb when I had the fuel lines reversed last weekend.
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Old Aug 16, 2012, 10:18 AM
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It may be "a" fix for some , perhaps not "the" fix for all . This was however just an experiment and that point has been made clear repeatedly . The fact is , a foul running engine is now powering the plane and seemingly running quite well .
This was/is just a starting point as Earl now also has an adapter that will allow the use of various glow carbs to further refine the choices .

In any event ; To find out , someone must first undertake to try .
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Old Aug 16, 2012, 02:40 PM
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Quote:
Originally Posted by Gary Cee View Post
It may be "a" fix for some , perhaps not "the" fix for all . This was however just an experiment and that point has been made clear repeatedly . The fact is , a foul running engine is now powering the plane and seemingly running quite well .
This was/is just a starting point as Earl now also has an adapter that will allow the use of various glow carbs to further refine the choices .

In any event ; To find out , someone must first undertake to try .
And kudos to your generosity of patience. If I spend $220.00 U.S., as I did, I don't expect to be buying an experiment or at best "a fix for some".

I wouldn't ask Mr. Chow for adapters and make it work parts. I would ask for an operational product.
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Old Aug 16, 2012, 08:15 PM
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I understand fully . It seems however some of us are drawn to the challenge of a less than perfect device , just for the heck of it .

I am quite certain Mr Chow is an honorable person and he is trying to put a decent product on the market . It is possible that he is in a bit over his head . Perhaps he will learn a bit from what has gone on here and other places an in turn makes changes and corrections .
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Old Aug 16, 2012, 08:49 PM
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Quote:
Originally Posted by earlwb View Post
I wish NGH had carb rebuild kits available, as it is easy to damage a diaphragm in some situations. That was one driving reason behind going with a Walbro carb. If I had problems I could put in a new diaphragm from a locally available rebuild kit. I did rupture a rubber diaphragm on the carb when I had the fuel lines reversed last weekend.

Earl, why not use a Walbro wt rebuild kit?


Bill M.
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Old Aug 16, 2012, 10:27 PM
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That is a really good thought.
Thanks for the tip Capt Quirk.
For some odd reason I was thinking that the NGH pump/regulator was really smaller than the Walbro carb. But it isn't, the diaphragms are the same size basically. Now there seems to be more than one version of the Walbro DT-WAT Repair kits out there. I found that the blue plastic diaphragm and the white teflon diaphragms from the kits with them it it, seem to fit just fine. I have a black diaphram too, but I forget which kit it came out of though.

I think Michael Chow should have said something about the carb rebuild kits would work.

So I can rebuild the pump regulator unit as needed. I think that ought to help out immensely. With the Walbro carbs it sometimes seems that "When in doubt, rebuild it" or replace the diaphragms at least. I was using kits intended for the WT-298 and WT-520 Walbro carbs. I think that both kits are the same now. But the different brands may have some different parts in them though.

This is the NGH OEM pump diaphragm


You can see that the blue plastic one fits OK


The teflon diaphragm also matches up pretty good too. But that one small hole might pose a problem if the cover gasket doesn't block it off.




I have a black one but I am not sure what carb kit it came out of, also it doesn't have a pump diaphragm on it, so I am not sure what the heck it does or what you use it for, unless it is some kind of a pumpless carb setup. There might be a odd ball diaphragm half piece in the kit it came from or something.


I think that the regulator diaphragm from many of the repair kits will fit OK. watch out for the little metal bump in the center, some carb kits don't have it.




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Old Aug 17, 2012, 02:12 AM
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Istanbul, Turkey
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Another suggestion to Mr.Chow;
To add separate idling jet into carb also with a separate idle adjust needle and independent High speed circuit also with a HSN on it.At idling HS spraybar should be totally closed by metering needle.
Maybe then regulator should not need any change because spring/needle will work near constant suction(thanks to independent LSN and totally closed high speed circuit.)
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Old Aug 19, 2012, 09:44 AM
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Well, we have had some pretty good rain storms roll through the past few days, so my back yard has turned into a muddy swamp. So I may or may not get to do any engine testing this weekend. But I did setup my first engine for testing later. I redrilled and tapped the engine backplate and the pump/regulator to use 8x32 dual barb fittings instead of the smaller OEM fitting that came on the engine and pump. I got to thinking that the small fittings are not allowing strong enough pressure pulses to work the pump diaphragm. I also needed to file a little off the length of the threaded portion of the fitting as it protrudes a little into the crankcase or pump chamber as well. I think what bothered me was how well the engine still ran when the fuel line popped off the fitting on the crankcase. It had no effect on the engine. So I got to thinking that the fittings have too small of a hole inside of them for good pressure pulses to reach the carb. Also the OEM fittings have a single rounded edge barb that doesn't grip the fuel line tubing all that well either. On the engine fitting, I also use a Dubro Fuel Line Clip for 1/8 inch ID fuel tubing (Number 678) too. The larger fittings allow me to use the larger 1/8 inch fuel tubing as well.

I also replaced the rubber pump diaphragm with a Walbro Teflon pump diaphragm as it tends to pump fuel more strongly as well. Just in case I replaced the regulator diaphragm too. Now these engine tests are an attempt to get the NGH carb and pump/regulator to work better or not. As I would much prefer using the OEM items as they are not huge like using a Wabro carb on the engine.

I do like Turk1's method of going out to a stretch of highway someplace and test run the engines that way. So I might just take the setup out to our flying field and have a go at it out there too. But it depends on if our flying field out there is in a mini-lake or not. Fortunately my neighbors at home do not mind me running engines out back, unless it is too early in the morning.







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