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older G38 with no choke

Old 04-22-2017, 04:05 PM
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Question older G38 with no choke

Hi there.
I cannot recall if you can start an older G38 (WT-6A carb without priming or choking) with just an electric starter? I don't remember if they can be because I haven't used one in 20 years! I have two (older) NIB that I just installed in my DS ME110 that will be completely cowled in. They have the Wt-6A carb with no choke. I will not be able to prime with my finger.....

Yes, or No?

Thanks
Bob T.
Old 04-23-2017, 04:40 AM
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RCFlyerDan
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IMHO.......as long as they have been started before, and the Walbro pump baffle is not stiff, you will just need a lot of battery power for the starter to turn it over enough to suck the fuel to the carb. Short fuel lines will help. What about putting a hole in the cowl too so that you can shoot some prime into the carb? Otherwise, on a 92 degree day, it could be frustrating.
Old 04-23-2017, 05:51 AM
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I too would add a small hole in front of the carb just big enough for a squeeze bulb nozzle.
Old 04-23-2017, 07:19 AM
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There's no access to the carb intake venturi as I have Tony Clark 90^ elbows installed on them so the cowl needs no holes cut into it to clear the carb. The inlet faces rearward and towards the firewall......

I've used these things many times long ago and you would think that I would recall something like this, but I don't. I must say that if they were mounted stock (no Tony Clark elbows back then) on an airplane 20 years ago they would've been sticking through the side of a cowl so I'll bet I was priming it with my finger....

I have them on a test stand right now but thought I'd toss the question out there to get some perspective. I can get them running but on the stand I have been priming with my finger. My battery used for my starter is weak and I can't crank it over too many times without it dying.....I have one on order.
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Old 04-23-2017, 07:41 AM
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That changes things a bit.
I bought a plane with a rear-mounted carb buried inside a fuse running a carb without a choke plate. The previous owner fashioned a plate that pivots on the face of the carb and covers the carb opening to help draw fuel and has a detent to hold it open or closed. A pushrod moves the flap and the setup works well. Perhaps you could try something similar

This product is also useful to keep a small amount of fuel close to the carb so it doesn't have to draw all the way from the tank.
QuikFire - Fuel Balancer and Filter - JL Power Products
Old 04-23-2017, 08:50 AM
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That quickfire is interesting. Sort of like a mini header tank. I will probably try to fashion a plate as your friend did only after I verify that they'll be too hard to start otherwise....I now regret not buying the newer carb and using it but I'm not looking back now given I already have the firewalls, linkage, etc. already built and fitted.

Thanks
Old 04-23-2017, 08:57 AM
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Most all Zenoah engines like to be started quite wet, a tip I got from the Zen guru Ralph Cunningham some time ago which really works. On cowled installs I have found that a small hole in the cowl right opposite the carb mouth to facilitate inserting a small brass tube from a primer type fuel bulb to prime via the carb's throat works great.
Old 04-23-2017, 09:03 AM
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Most all Zenoah engines like to be quite wet for starting, a tip given to me by Zen guru Ralph Cunningham which work very well, so using any of the aforementioned options suggested to allow priming via the carb throat will certainly aid starting.
Old 04-23-2017, 02:53 PM
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You are really going to need a choke or primer setup. Cold, first time of the day starts will be very difficult without. Sometimes even after the first start a well tuned engine might want choked to start depending on how much it cooled off since the last run.

It would be quite easy to bend up some 1/8" brass, copper, or aluminum tube to allow shooting some fuel for priming into the carb, and could be made unobtrusive. A simple slide choke that rotates to cover the carb for choking would also be easy to make and hook up. I have done it many times. Numerous weedeater and chainsaws use this type choke.

In any case, trust me; you are going to need a choke or priming setup.

AV8TOR
Old 04-23-2017, 04:48 PM
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Ok, thanks. I'm working a simple choke cover. If that doesn't pan out then I'll go with a tube.

Bob T.
Old 04-24-2017, 09:57 AM
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The "slide over the carb throat" type chokes use a small outside diameter flat washer, a large outside diameter flat washer, and a large outside diameter wave washer. The small diameter washer goes on first, and provides a space for the choke plate which has a larger diameter hole that fits around the small flat washer. Then the choke plate goes on, sitting flat against the carb with its large mounting hole situated around the small washer. Then the larger o.d. wave washer goes on, which holds the choke against the carb and provides friction so the choke will retain its position wherever you set it. Lastly, the large o.d. flat washer goes on to retain the wave washer, and then the nut. This all allows proper choke operation, while still allowing you to tighten that carb mounting nut to prevent vacuum leaks.

Hope that makes sense.....

Edit/addendum: Note that the small diameter washer must be the same thickness as the choke plate or preferably slightly thicker, to allow choke movement. Also note that the choke should completely and firmly cover the carb throat to provide proper choking action.

AV8TOR

Last edited by av8tor1977; 04-24-2017 at 10:08 AM.
Old 04-24-2017, 10:21 AM
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Whoa, I'm going to have to draw that out. What I'm missing in that explanation is the way the 'choke' operates. It it like a shutter operation, sliding in and out of the intake on a single pivot?

Bob T.

P.S. I found this in another thread here on RCU...Is it similar to this?
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Old 04-24-2017, 10:32 AM
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av8tor1977
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Yes, exactly.

AV8TOR
Old 04-24-2017, 10:35 AM
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Well, hang on. That one appears to use a third bolt. The method I described just uses one of the original carb mounting bolts. It sounds more difficult writing it all out than it is in practice.

AV8TOR
Old 04-24-2017, 11:00 AM
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Yeah, I sort of wondered the same thing as to why a separate screw.....I'm sure it can be done without one.
Old 04-24-2017, 11:31 AM
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The one airplane I have with that type choke is 250 miles away. I have looked at hundreds of my pictures and looked at a bunch of online engine schematcs and just can't locate a pictorial example for you. Do you think you understand my description??

AV8TOR
Old 04-24-2017, 11:44 AM
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Havng said all that, in your case, I would be sorely tempted to grab a long piece of 1/8" aluminum tubing and bend up a primer line going from the carb throat to the top or side of the cowl. Very quick, easy, and equally unobtrusive as a choke linkage wire or knob. Your carb runs downhill to the engine, so priming would work really well. Choking an engine to start requires several to sometimes numerous prop flips. With a primer setup, once you figured out exactly how much fuel to squirt in, you could have "one flip" starts....

On my airplanes that don't have cowled engines, I use a somewhat different starting procedure than most. Instead of choking, flipping till it starts and then stops, then opening the choke and flipping till it starts, I instead use my finger to choke the engine. With my finger tightly over the carb throat, I turn the engine over by hand until my finger gets good and wet. Then I turn on the ignition, and almost always with just one flip the engine is running.

AV8TOR

Last edited by av8tor1977; 04-24-2017 at 11:53 AM.
Old 04-24-2017, 01:46 PM
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Yeah, I'm leaning that way too because after I start stacking hardware and a plate on the carb I'm getting pretty close to the firewall. There's plenty enough room for airflow but mechanical stuff starts getting in the way for even a manual choke rod. So, it's probably going to be a primer tube.....it's much easier too.
Old 04-24-2017, 02:20 PM
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Originally Posted by av8tor1977 View Post
On my airplanes that don't have cowled engines, I use a somewhat different starting procedure than most. Instead of choking, flipping till it starts and then stops, then opening the choke and flipping till it starts, I instead use my finger to choke the engine. With my finger tightly over the carb throat, I turn the engine over by hand until my finger gets good and wet. Then I turn on the ignition, and almost always with just one flip the engine is running.

AV8TOR
That's my way of doing it too and it works like a charm, however I normally need a couple flips to get most of my engines going but still nothing near the arm weary action I see other fellows doing when starting their cold engines.
Old 04-24-2017, 04:10 PM
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Here is an example similar to what I have :

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Old 04-25-2017, 02:07 PM
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av8tor1977
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Thanks for the pic! That is exactly what I was describing and exactly the same setup I have on one of the planes in my fleet. It came off a chainsaw, but I just can't remember what brand/model now. I have also made them from scratch though; just buying the washers required. If we knew what chainsaw they came on, it would be really cheap to buy the pieces. If I get a chance, I'll research it some more later. It would be good info for us to have in any case. You never know what future projects might entail....

AV8TOR
Old 04-25-2017, 02:13 PM
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av8tor1977
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Hey W8YE, you're a "chainsaw guy". What saws come with a choke like this??

AV8TOR
Old 04-25-2017, 03:27 PM
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McCulloch

http://www.ebay.com/itm/McCulloch-Chainsaw-610-CHOKE-PLATE-94151-PM-605-645-650-655-E-B-3-4-3-7-OEM-BIN-/152489555991?hash=item238115f817:g:kI4AAOSwUV9WoDp h"=
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Last edited by flyinwalenda; 04-25-2017 at 04:58 PM. Reason: Fixed Link
Old 04-25-2017, 04:40 PM
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Linky no worky.....
Old 04-25-2017, 08:50 PM
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It worked for me.

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