Gas Engine - Choke Push Rods: Need Some Suggestions
 

Hi Guys,

I have a DLE-35RA Gas Engine. Being fairly new to Gas Engines I understand that to reduce any chance of radio interference that you need to use Non-Metallic type push rods. I have tried several different types of push rods to find the right set up. Here's the direction I am headed in so far.


The manual suggests using a "Ny-Rod" type set up for the Throttle linkage.


I have moved towards the older type of (Dubro / Great Planes) Nylon Push Rods. The "Red Tube with the Yellow Nylon inner tube push rod" with a threaded metal rod about two inch long with a 90 Deg. and a Faslink set up at the servo end. Then at the Throttle end I have a 1 inch threaded rod and a ball link attached to it. This seems to be working out pretty good.


However, the Choke is giving me some Grief. It is pretty stiff and some of the control rod set ups would not work on the Choke.



The "Two Issues" are with the Choke Arm.



1. When in the closed position, which is approx. 1/8th " away from the firewall. So there is not a lot of room for any type of linkage. ex. Nylon Clevis, Socket Ball, Right Angle w/Wheel Collar etc.

2. The bend in the path of the control rod from the servo to the Choke has some curves to it. I tried a few locations, but no matter where it ends up there are still some curves to deal with......




So my Question is at this point:

Is how exactly important is the Choke being insulated by "Nylon" as opposed to "Metal on Metal" Because I can come up with several scenarios that will work but there is some "Metal on Metal" involved. At least on one end of the control rod, most likely the Engine side of the run. Would this be OK???



So any suggestion with the Choke would be much appreciated......


Thanks

Ed :cool:

Here's how I do it. The choke is just as important if you want your airplane to last a long time. Try a manual setup for the choke. Dan.



http://www.rcuniverse.com/forum/atta...mentid=2106054

Nice set-up on choke & ignition. Did you make the advance unit? Is there a bearing under the white piece or is it in a groove you made?

Thanks Capt,n

Captain, The white ring is made out of nylon and is used for the mechanical advance the Brisons used to come with. It is riding on the crankcase. Two inside clip rings keep it in place. There are two grooves in the case for the rings. The nylon ring can be fixed in position for use with the ignition modules with electronic advance. I’ll upload an image of one of the engines that has been changed over and you can see that the pushrod to the ring has been removed.


http://www.rcuniverse.com/forum/atta...mentid=2106082

Throttle & Carb Linkage Pics:
 

Hi Guys,



One of my issues is the lack of space for the Choke. I have the Throttle worked out and the Choke somewhat where I need it to be. Check out the 2 Pics of enclosed. The Choke is working but the strain is quite a lot on the servo. There's a lot of servo strain closing the choke & opening, but once it's there it seems to be doing the job. I worry about the overall drain on the battery, but I got to think, how much I will actually be using it putting a load on the battery.

Note: The Choke - I am using the old "Sullivan Type NY-Rod" The "Red tube type with the Yellow Nylon Rod inside" is not a steel rod all the way thru. It is a 1" steel rod screwed into a Yellow NY-Rod going thru the firewall to the servo. At the servo end another 2" steel rod screwed into the NY-Rod with EZ-Connectors at both ends.


I wish there was a way to remove the stiffness of the choke. It seems like there is some kind of detent or ratcheting ball that locks it in when going from closed to open position.

Any ideas on how to remove the detent on the choke or to make the choke not so stiff?



Thanks

Ed :cool:

If you are on 2.4 forget it. All of that interference crap has gone away with 72.

Old posters never die, they just flame away

What makes you think I am not using 72Mhz???

I have a Futaba 9CAP Super. Which I have over 16 planes on it. For the amount of flying that I do now a days it does not pay for me to switch over. The expense of 16 + receivers would be dumb for me to go that route. As a matter of Fact the do have a Spektrum DX7 which is about 3 years old that I won. I have not used it yet.


LOL......

Thanks

Ed

Plus one on the metal pushrods. No longer an issue.

Just asking, but did you remove the spring and the ball-bearing detent from the carb body?

A LOT of the guys on here have not flown gas on 72. If that's your plan, I'd suggest you mention you're flying 72 whenever you ask a question.....

I think you should get out that spectrum and get rid of those 16 receivers while you can.

Why?
1) You dont have to worry about others shooting you down.
2) you dont have to worry about interference from other sources unless it wipes out the entire band
3) cheaper receivers.
4) Less Tx current drain. Your battery lasts longer.
5) much shorter antennas.
6) More rugged receivers. No fragile crystals or IF cans

WHY NOT!!!!
1. Flying over 42 years I have never been shot down. I have never worried about being shot down since we follow good Freq. Control at our field. Yes I am one of the last few (maybe 15%) still flying on MHZ but if it "Ain't broke Don't Fixit"
2. I have never had any interference that is worth worrying about that was not user error on my part.
3.Cheaper.... The 16 I have are FREE..
4. As long as there's no binding and you follow good battery maintenance and don't over fly the batteries expected flight time. You should be fine...
5.Since I also fly Q-500 I have a short whip, so my antenna is approx. 12".
6. I only use the Hitec Supreme 8 channel receivers for the most part and in the bigger planes the Futaba PCM units.

I fly about once or twice every other month between March & October... So I don't see the need for changing something that works fine..

Thanks

Ed

If you are not worried about interference why are you asking about pushrod installation?
A couple of things I forgot
1) the new systems provide telemetry and voice alerts. It makes things much safer and more enjoyable.
2) 2.4 systems have reduced latency. But if you are happy with that Futaba PCM I guess it wont mean much to you. Its about the worst there is.

CHoke Linkage
 

Hi Lifer

Are you referring the spring and screw connected to the Throttle body and throttle linkage, Then Yes I did. Is there anything in the Choke internally that will remove some of the stiffness?

Using basically 2 metal rods connected with a 2 " section of Yellow NY-Rod inner tube to keep it as stiff as possible while breaking up the metal on metal continuity. Overall the length is 14 inches.



http://www.rcuniverse.com/forum/atta...mentid=2106173



Thanks

Ed

You can remove the screw that attaches the butterfly to the bar. Note exactly and mark the position of the butterfly before you remove it. After doing so carefully move the mounting bar, there is a very small ball that is spring loaded that will fly out , watch your eyes, This will release the tension, replace the butterfly, now the choke will move as easy as the throttle. Hope this helps.

Generally I am not worried about any interference because when I am familiar with what I am working with. In this case I am not. I have not had any R/C Gas experience and I am trying to cover all bases. That brings up a good point. The interference that is described in the manual is it Radio interference or interference that can cause havoc with the electronic ignition system?Another words any metal on metal interference is it in relationship to causing timing issues or Radio issues?

PS. I Love my CAP Super radio. I have won a lot of contests and races with it and I am very use to the layout of the radio.

Thanks

Ed

Ed, go here to see how to remove the detent. There's nothing wrong with using gas engines on 72. There never was. Dan.

http://thecubden.org/thecubden/how-t...lbro-choke-fix

The interference they are talking about is to the radio. It will not interfere with the ignition.
If a long wire is connected loosely to the engine, it will make and break contact under vibration. Static electricity will build up on the rod and cause sparks when the contact breaks.That spark contains much rf energy and will interfere with your 72 system.
You can stop it by insulating the rod with a plastic connector or bond the rod to the engine with a flexible wire

Hi Guys,

Thanks to Dan, Lifer & JMpups,

I figured it out. I enclosed a pic because I know everyone loves pics. I was able to remove the ball & Spring that was placing undue pressure on the Choke. With a servo controlling the Choke there is absolutely no need that I can see why it needed. I was able to remove it and now the choke linkage works flawlessly.



Thanks again for you guys that helped with positive info.



http://www.rcuniverse.com/forum/atta...mentid=2106175http://www.rcuniverse.com/forum/atta...mentid=2106176



Thanks

Ed

Here are a few photos of various types of carb linkages. Two are a VV 20 with a mechanical choke linkage that comes out the front of the cowl.Two are of a DLE 55 that uses a choke servo behind the firewall. Bolt on ball links used wherever possible for security. Pushrods are steel and I don't worry about them. Before switching to 2.4, I used the same setups on 72 for many years also without problems. Servos are usually mounted a few inches behind the firewall in front of the tank. I always extend the choke arm for ease of use.


http://www.rcuniverse.com/forum/atta...mentid=2106180http://www.rcuniverse.com/forum/atta...mentid=2106181http://www.rcuniverse.com/forum/atta...mentid=2106178http://www.rcuniverse.com/forum/atta...mentid=2106179

Be sure to red Loctite the screw that holds the choke plate on the shaft. You may have damaged the threads in the shaft when you removed the screw if you did not grind off the end of the screw first. Dan

Glad to have helped in some little way. Send me a PM if I can help in the future.

Dan


What do you mean by grinding off the end of the screw? The screw came out pretty easy. As easy as one would expect a screw with Loctite to be removed would be I had no issues screwing it back together other then a slightly stiff. I made sure not to cross thread it and made sure the butterfly plate lined up just right before snugging it down.



Thanks

Ed

The thread end of the screw should have been swaged (smashed flat or have an X pattern) to prevent the screw from coming out. As Dan suggested, if this is not ground off before removal the screw can damage the threads in the shaft making it difficult to retain the screw even with loctite. Steel shafts usually survive but brass shafts can actually break where the screw passes through. I always use a new screw for reassembly and prefer green wicking Loctite rather than red. Green is applied to the threads after assembly and in very sparse amounts!

I leave all springs and detents in place on my Walbro or Walbro clone carbs. I don't see any reason to modify or remove anything. I add longer arms when necessary as shown in my photos above which gives plenty of leverage to overcome most resistance. On the first photo I posted, the arm was in interference fit to the firewall so I relieved the firewall for clearance. You do what you have to do to make things work.

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