Glow Engines Discuss RC glow engines

.049 COX WON'T STAY RUNNING

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Old 05-06-2011, 06:12 AM
  #1
marwen1
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Default .049 COX WON'T STAY RUNNING

I HAVE A SMALL .049 COX GENERIC ENGINE WITH A SMALL TANK ATTACHED ON THE BACK.

IT WILL FIRE UP WITH A POWER PANEL AND THE CONNECTOR CLIPPED TO THE GLOW PLUG.

RPM'S CHANGE OK WITH THE ADJUSTMENT OF THE NEEDLE VALVE BUT THE MOMENT I TAKE THE CLIP OFF THE PLUG - IT QUITS

SUGGESTIONS PLEASE

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Old 05-06-2011, 06:14 AM
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Default RE: .049 COX WON'T STAY RUNNING

Lean it out! If it's quitting when you take the heat off, it's too rich. Too much fuel is hitting the coil, taking the needed heat away.
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Old 05-06-2011, 06:37 AM
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Default RE: .049 COX WON'T STAY RUNNING

Or it could be a bad glow head.
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Old 05-06-2011, 06:39 AM
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Default RE: .049 COX WON'T STAY RUNNING

Definetly. But best start with the easy, "free" changes before you start replacing things/taking them apart
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Old 05-06-2011, 07:25 AM
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Default RE: .049 COX WON'T STAY RUNNING

Make sure that you have FRESH (that means newly opened) fuel.
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Old 05-06-2011, 10:10 AM
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Default RE: .049 COX WON'T STAY RUNNING

Use 1/2a fuel, not your normal 5/10/15% nitro fuel will help.
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Old 05-06-2011, 11:20 AM
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Default RE: .049 COX WON'T STAY RUNNING


Quote:
ORIGINAL: C185Pilot

Make sure that you have FRESH (that means newly opened) fuel.

New Plugs - I think I have about a doz. or more.

I thought I spotted a drop of humidity in the syringe.

In fact, I think this fuel is over 1.5 years old. The container I had it in was plugged tight... I'll try to lean it out... If that don't work

a new Qt of - what ??? 25% nitro

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Old 05-06-2011, 11:47 AM
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Default RE: .049 COX WON'T STAY RUNNING

20% castor oil is best, between 10% and 30% nitro.
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Old 05-06-2011, 12:03 PM
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Default RE: .049 COX WON'T STAY RUNNING

Hi!
...And a 5x3 or 6x3 prop (if it's a .0.049 engine).
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Old 05-06-2011, 05:07 PM
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Default RE: .049 COX WON'T STAY RUNNING

Fuel at 1.5 years is not fresh especially if it is in a plastic jug. Believe it or not water molecules will permeate the plastic and foul the fuel. I agree on the 20% castor and 25-30% nitro.
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Old 05-06-2011, 07:53 PM
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Default RE: .049 COX WON'T STAY RUNNING

Cox engines are chrome piston steel sleeve motors, best to use castor for good sealing and also the ball and socket wrist joint. They starve a bit under the piston and it is good to have all castor there. It is one of the hotest parts of the engine and still has to move.

If you are leaning out your motor to get it to run with a new plug, and your using normal (synthetic oil) model fuel, you might run into wear problems. Two ounces of castor to a normal gal of synth blend should be fine. It will also slightly raise your compression so maybe add a head shim too.
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Old 05-06-2011, 09:05 PM
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Default RE: .049 COX WON'T STAY RUNNING

If you are not using at least 20% nitro with all castor they engine will not run right.  They are set up for about 25% nitro and 20 to 25% castor oil.  The plug will be to cold for lower nitro, and the compression will be poor without a lot of castor oil.
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Old 05-07-2011, 05:19 AM
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Default RE: .049 COX WON'T STAY RUNNING


Quote:
ORIGINAL: jetpack

It will also slightly raise your compression so maybe add a head shim too.

That some good input.

Those dozen plugs that I have are a mix of standard as well as High Compression.

I'll have to get some shims at the LHS

thanks again

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Old 05-07-2011, 06:54 AM
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Default RE: .049 COX WON'T STAY RUNNING

Quote:
ORIGINAL: Sport_Pilot
If you are not using at least 20% nitro with all castor they engine will not run right.
I'd never run any Cox engines until my son gave me quite a few of them so I thought I'd give them a try with my usual 80/20 castor fuel. All of them, from a Babe Bee to a Tee Dee .049, gave me one flick starts (I didn't bother with the spring starter) and they all ran beautifully. Sure, they'll give more revs with nitro but they certainly don't need to it to run perfectly. Is this another myth busted?
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Old 05-07-2011, 07:23 AM
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Default RE: .049 COX WON'T STAY RUNNING

Adding one or two shims on this size engine has a noticable effect you'll see it in ease of starting and lower power output. Going past three shims you won't see much power but it will still run and start fine. See how it does with three shims to start with, then experiment and start taking one shim out at a time until you have good luck with both starting and the amount of power you see. I always remembered to run two shims with a TeeDee/head. One shim always seemed to want to overheat the engine.

Before the only way to buy Cox head shims was to buy a glow head but I see now that Cox sells them seperate. Also be sure you know how many shims are in your cylinder to start with. I have seen shims in the top of used engines that you swear weren't in there, they tend to hide.
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Old 05-07-2011, 07:58 AM
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Default RE: .049 COX WON'T STAY RUNNING

YEP!! YEP!! YEP!! Amazing what one can do with fresh fuel.

Fresh fill up, one flip of the spring and VOILA - I barely had to tweak the RPM's and it went up to 18K or better.

With a little effort I can probably get it up another 10% or better.

All I want to do is to get my GENTLE LADY - 2 METER - SAILPLANE up within a couple of weeks.

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Old 05-07-2011, 09:06 AM
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Default RE: .049 COX WON'T STAY RUNNING

The fuel I got from the LHS was 20%/16% caster. I was wrong with that RPM more like 14500K

I have a short tri blade on it. - I assume that the small tank is a .5 oz - no shim With a full tank running wide open, I'm only getting 30-35 seconds

How can I increase my time?

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Old 05-07-2011, 09:08 PM
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Default RE: .049 COX WON'T STAY RUNNING


Quote:
ORIGINAL: downunder

Quote:
ORIGINAL: Sport_Pilot
If you are not using at least 20% nitro with all castor they engine will not run right.
I'd never run any Cox engines until my son gave me quite a few of them so I thought I'd give them a try with my usual 80/20 castor fuel. All of them, from a Babe Bee to a Tee Dee .049, gave me one flick starts (I didn't bother with the spring starter) and they all ran beautifully. Sure, they'll give more revs with nitro but they certainly don't need to it to run perfectly. Is this another myth busted?
The will run that way, but at about half power (or so it seems). The plug is just too cold for low nitro.
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Old 05-08-2011, 06:50 AM
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Default RE: .049 COX WON'T STAY RUNNING

QUIRKEY LITTLE THINGS - AREN'T THEY?

If I change to a somewhat normal plug - will that help?

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Old 05-08-2011, 09:25 AM
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Default RE: .049 COX WON'T STAY RUNNING

There is actually nothing particularly quirkey about them, just like any other glow engine they just need the correct fuel and prop. 20% all castor fuel with 10-20% nitro and a 5x3-6x3 prop.

The heads that take regular glow plugs are down on power unless you seal the threads and rework the head to get the correct compression ratio. You can get original plugs from coxengines.ca or the new replacement plugs from Merlin.
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Old 05-08-2011, 09:39 AM
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Default RE: .049 COX WON'T STAY RUNNING

I guess the only reason I am using a 20% NM/ 16% Oil is - that is all my LHS had to offer at the time I bought it.

I am using a 5/3 Pusher Prop. In fact I took the spring off so that I wouldn't loose that extra 500 RPM (or so)

"Querkey" was simply a figure of speech!

I find it so bloody hard to "say" something while writing without upsetting someone's applecart.

Y'all have a great Mother's Day!

Gotta go. It's time I got out and went to my flying field and gave the boys a hand cleaning it up after our unusually large snowfall this past year

They don't call this place WINTERPEG for nothing.

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