SJ 60LX Glow plug=candy  
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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> Jett Engineering Support >> SJ 60LX Glow plug=candy
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SJ 60LX Glow plug=candy - 1/26/2008 10:32:36 PM   
SavAxiInf



Posts: 54
Joined: 4/3/2004
From: Akron, OH, USA
Status: offline 		I just purchased a Jett SJ 60LX and I am in the process of adjusting and breaking in. I am running it as it says in the breakin procedure.
The problem is that it is eating glow plugs like candy.I run a 1/2 of a tank thru it then let it cool, When I go to start it up again and fill the tank, the glow plug is open.
So far 3 plugs. I am usinga 10x6 apc prop, os#8 and 15%nitro. Is there some thing that I need to be doing that I am not ?
       Post #: 1

RE: SJ 60LX Glow plug=candy - 1/27/2008 9:17:01 PM   
rmenke


 

Posts: 1664
Joined: 6/25/2004
From: Merced, Ca., CA, USA
Status: offline 		SavAxiInf:

Gut reaction, your running her lean somewhere in the low or high circut of the carb, maby too much comporession. Are you breaking in at 5% as you should with 2-4 oz of castor added? You should get 18K with the 8.8 X 8.75 or very close, fat. If not, go to less pitch. Try adding another washer to the plug. If that solves the problem, call Dub for a shim. You can save some grief with plugs with Dubs Merlin HD plugs over the OS 8 or MC9 or others, allthough I did get a bad batch of plugs last lear good for start and 1 run from Merlin. I have two of these egines, love them to death, no problems anywhere. You gotta follow Dubs breakin proceedure of you will pay a penality at some point. I do run the OS 8 as a backup only, no problems. With TLC, the thing will run longer than you will. ENJOY

(in reply to SavAxiInf)
       Post #: 2

RE: SJ 60LX Glow plug=candy - 1/28/2008 10:31:23 PM   
bob27s



Posts: 4423
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		thanks for writing.....

sorry for the delay.

First off....
You are not following the break-in instructions. That is absolutely critical. This engine is a whole other level of performance than any other sport engine out there.

This is a quote from one of the instruction/caution sheets that comes with the 60LX engine...

"CAUTION!!!!!!!!


THIS ENGINE (___.60LX____) IS EQUIPPED WITH A DIFFERENT MUFFLER OR TUNING SYSTEM THAN DESCRIBED IN YOUR INSTRUCTIONS. PROPELLER RECOMMENDATIONS HAVE BEEN DISCUSSED WITH JETT ENGINEERING. USE EXTREME CAUTION WHEN DEVIATING FROM THESE RECOMMENDATIONS. THE USE OF TOO LARGE A PROPELLER CAN LEAD TO LEAN RUNNING AND ENGINE DAMAGE.

THESE ARE SOME SUGGESTIONS:

APC

10X6
9X8
9X9

PROPELLERS SHOULD BE MATCHED TO RPM. THIS ENGINE LIKES TO TURN MORE THAN 17000 (PEAK, NOT LAUNCH), SO SIZE YOUR PROPS A LITTLE SMALLER THAN USUAL AND LET THE ENGINE TURN!!!! "


Break-in prop for a 60LX can not be a 10x6 prop. You want to use a prop one inch less diameter, or one.two "pitch" sizes lower in size for break-in. Chances are the engine is not getting to proper RPM and is ended up lean/hot. The 10x6 prop is the largest size recommended for the engine, and is suitable only after complete break-in and perhaps a bit of run time.

For break-in, use a standard blade APC 9x6, 9x7, racing type 8.75x8, 8.5x7.25 or an APC 10x6 prop clipped to 8.5" diameter and balanced.

Mount the engine on a test stand. Start with the engine rich (5 turns open). Using any of the props noted above. Start the engine at full throttle, lean it out so it is in stable but rich 2c, and remove the glow driver. Then lean it a bit more ... take the engine to 18,000 rpm and let it run there. Do not go to peak rpm with that prop. It will be running a bit rich at that rpm with the light prop load. That is what you want. Run it like that at least 20 minutes.

On the following tank, replace the prop with a flight prop - I suggest a 9x8 or your 10x6 prop. Take the engine to full throttle, lean it to peak rpm (find it very briefly, then back off immediately) then back off 800-900 rpm. Note the rpm, approximate needle setting - that is where you want to set it for first flight. For flight, you want to launch this engine at least 800 rpm rich down from peak rpm.

Do not use an OS #8 plug. It is too cold for the 60LX engine when it comes to throttle response... but it is ok for the top end. McCoy 56, Merlin HD Hot (supplied with engine), Rossi 2 or 3, Enya 3, OS A3 are decent choices. I personally prefer the K&B 1-L and K&B HP plugs. The OS F plug is good too, after initial break-in.

The engine blows plugs for one main reason - a lean run. Also if it is getting hot from being overloaded, it can create its own lean condition and toast the plug. Trying a different plug will not prevent a blown plug.

Double check the fuel system on the test stand. Be sure it is mounted on a foam pad so it does not create foam or air bubbles.

Same goes for the airframe - make sure it is 100% foam isolated, or are alternately using a bubble-free fuel system.

The 10x6 prop is the very largest prop you want to use on this engine. Only try it after break-in, and preferably after a test flight or two.

If you need some help along the way, drop me a note. I'm not all that far from you it appears.

Bob


_____________________________

Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to SavAxiInf)
       Post #: 3

RE: SJ 60LX Glow plug=candy - 1/28/2008 11:05:27 PM   
fizzwater2


 

Posts: 601
Joined: 8/16/2004
From: Paola, KS, USA
Status: offline
quote:

ORIGINAL: bob27s

.... Run it like that at least 20 minutes.


Bob


Bob, just for my information - do you recommend short runs with cooling between them, or longer runs to add up to 20 minutes? Just wondering.

Thanks

_____________________________

no matter where you go, there you are..

(in reply to bob27s)
       Post #: 4

RE: SJ 60LX Glow plug=candy - 1/28/2008 11:22:34 PM   
SavAxiInf



Posts: 54
Joined: 4/3/2004
From: Akron, OH, USA
Status: offline 		Bob

I guess I had better go on a plug and prop hunt.

Thanks

(in reply to fizzwater2)
       Post #: 5

RE: SJ 60LX Glow plug=candy - 1/29/2008 6:40:24 PM   
bob27s



Posts: 4423
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		You can use the 10x6 you have on hand ..... if you do not mind cutting it a bit.... cut the 10x6 down as suggested. (good tool for the future too... reference prop, and also useful for break in of just about any 46-60 size engine)

Very likely what ever plugs you have on hand will likely work fine once you get the rpm up and the prop load down.


_____________________________

Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to SavAxiInf)
       Post #: 6

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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> Jett Engineering Support >> SJ 60LX Glow plug=candy
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