Help! Can't keep TH .61 running inverted in a GP J3 Cub!

I use a third line also and on cowled engines I drill a hole in the cowl that is a snug fit for the fuel line. I use a little aluminum button sort thing to stick in the end of the line and keeps it from pulling back into the cowl. Not sure what these things are. Found them in some parts drawers at a hardware store a few years back. They have a button head about 1/2" in diameter and the shaft is about

3/4" and fits inside the line real snugly. With the line cut the right length it looks a lot like a fueling valve .

I agree. I've seen nothing but trouble , regardless of brand. Maybe there are some out there that work but I haven't seen one. I would love to have one that DOES work.

Reply to
Ken Day
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Ken,

Those sound like fuel dots. A good source is Central Hobbies.

Reply to
Paul McIntosh

The first thing to understand and acknowledge is that the engine has no way of knowing that it is running inverted. It is just a machined lump of materials.

Assuming that the engine is in perfect mechanical condition, i.e., all fasteners are at proper tightness, there are no airleaks, the engine is fitted with the recommended glowplug, propeller size is within spec and the proper fuel is being used, the problems that you are having must be related to the fuel delivery system.

A setting of the needles in an inappropriate manner could also contribute to the problem, as well as the engine not being properly broken-in and not being ready for normal service.

While the initial handling and starting of the engine is changed somewhat by the fact that it is inverted, after it is running, its operating position is of no consequence. The latter fact is difficult for some folks to work into their noggin, but it is true.

Stale or contaminated fuel is also a possibility, if you haven't addressed this as of yet.

Do not rely upon the model's manufacturer or designer to have set up their model in proper fashion, i.e., tank height/vibration isolation.

One of the things that I learned long ago was to never let any part of the fuel tank touch any solid part of the model. It will lead to fuel foaming, which is a bear to detect. Why? Because when the model is sitting on the ground, the fuel may not foam, but as soon as it takes off and is in the air to freely vibrate as it pleases, that is when the fuel foaming begins.

Obviously, with what I have written above, it is clear that any model that has its fuel tank neck sticking through the firewall, is designed poorly and is prone to problems.

I have seen many folks quit the hobby because they would not believe me on this topic and they insisted upon using the factory setup - became discouraged at constant flame-outs and then gave up in disgust.

I do not sell fuel tanks, therefore there is no reason for me to lie about such a thing. There is no profit motive involved at all. But some folks simply cannot believe that their model's manufacturer is either inexperienced, stupid or all of the preceding.

Oh, and even if nothing is touching the fuel tank, or its brass/aluminum fuel lines, it can still vibrate for other reasons, such as having the foam that is packed around it too tight. No, rubber banding it to the floor won't work either.

I did my bit by telling you. What you do is up to you.

Ed Cregger

P.S. This is a message to all newbies, not just the original poster. In fact, some of what I have said may not apply to the original poster at all. I know nothing of his experience level.

Reply to
Ima Heinemann

OK! The weather FINALLY cooperated and I had a chance to fly the cub with a friends O.S. 61 in it. Again ... the fuel system was not changed from the previous, we simply mounted this engine exactly the same as the TH .61 engine (inverted).

The plane flew fantastic! Never once did it die, or act like it was going to. Flew two tanks of fuel through it (about 40 min of flight) and I was having a ball! Finally got some flight time.

So I guess it's the engine itself that is the problem. It's going back.

Thanks for all the suggestions! If nothing else, I'm a little more educated than I was to begin with.

Cheers!

Storm

Reply to
Stormlord

On Fri, 21 Oct 2005 07:35:51 -0500, "Stormlord" wrote in :

Thanks for the update, Storm.

As my natural theology teacher used to say, "O great mystery of being!"

Marty

Reply to
Martin X. Moleski, SJ

I would pay money ($2.00) to know the answer to this one.

Glad you came to a conclusion.

Good flying

Ed Cregger

Reply to
Ed Cregger

-- indoruwe

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Reply to
indoruwet

On Wed, 26 Oct 2005 14:32:11 -0500, indoruwet wrote in :

I sent the following to your address above by e-mail:

Reply to
Martin X. Moleski, SJ

Marty:

My address above (as shown on my reader, I use Firefox and read thi forum through "RC Groups > Hosted Forums > USENET (aka Newsgroups) rec.models.rc.air". is NOT my e-mail address, which may be the reason why my e-mail to yo has also not gone through.

use : snipped-for-privacy@yahoo.com for e-mail to me and tell me where to sen the file (PDF 450 K

-- indoruwe

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Reply to
indoruwet

On Thu, 27 Oct 2005 15:46:21 -0500, indoruwet wrote in :

Thanks.

My e-mail address is > snipped-for-privacy@canisius.edu. I've sent an e-mail to the address you gave in the last post.

Marty

Reply to
Martin X. Moleski, SJ

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