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jeet longer stroke

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Old 09-18-2008, 11:58 AM
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angelgarcia
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Default jeet longer stroke



I HAVE 1 MACHINE LS QM40 AND , Q500 LS , I NEED MORE PERFORMANCE ,

WHAT HAPPEN I PUT Cylinder Shim IT IS THIS GOOD OR BAD FOR THIS MACHINE AND IF IT IS GOOD .

HOW MANY SHIM IN THE CYLINDER AND THE HEAD I NEED PUT FOR MORE PERFORMANCE IN THE 2 MACHINE

WHAT IS YOUR RECOMMENDATION

THANKS. ANGEL GARCIA C.
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Old 09-18-2008, 12:19 PM
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Default RE: jeet longer stroke

Hi Angel....

Thanks for writing.....

The way Dub sets up the racing engines when they are sold is the best possible performance setup.

Liner shim is not recommened.

Head clearance is typically set to .012" to .015"

The key to making the engines run is prop selection.
Do not run the same props the Nelson guys are using. It will not work.
The engines are very different in that respect.

8.8x8.75 for the QJ-2 Q-500 engine 7.8x7.75 for the QM-2 quarter midget engine.
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Old 09-18-2008, 01:01 PM
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Default RE: jeet longer stroke

HI Bob Brassell


THE LAST WEEK I HAD RACE IN GUADALAJARA MEXICO 99.9 % HAVE NELSON LS ONLY 2 PEOPLE AND ME HAVE JEET THE NELSON IT IS VERY FAST

WHAT YOU THING I NEED DO.

IN THIS RACE I USE THE PROP 8.8 X 8.75 I SEE THE AIRPLANE SLOW

TANKS
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Old 09-18-2008, 01:47 PM
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Default RE: jeet longer stroke


ORIGINAL: angelgarcia

HI Bob Brassell


THE LAST WEEK I HAD RACE IN GUADALAJARA MEXICO 99.9 % HAVE NELSON LS ONLY 2 PEOPLE AND ME HAVE JEET THE NELSON IT IS VERY FAST

WHAT YOU THING I NEED DO.

IN THIS RACE I USE THE PROP 8.8 X 8.75 I SEE THE AIRPLANE SLOW

TANKS

The QM2 quarter midget 40 engine will run with and beat the Nelson engine as is. Very impressive engine.

The QJ2 is right now about 2 seconds slower than the best Nelson q-500 setups. It can run 1:08 - 1:10 consistantly (even with my rusty thumbs). With good thumbs, it can squeek out a 1:06 or somewhere close. It will not run in the 1:04-1:06 range some of the top end Nelson guys are getting. Props 8.8x9 and 8.8x8.75 seem to be best. At the NATS, Dub and mike flew the 8.75 pitch.

Some design updates coming for the Q-500 engine over the winter.
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Old 09-19-2008, 11:08 AM
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Default RE: jeet longer stroke

WY IN THE NELSON PUT SHIM IN THE CYLINDER
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Old 09-19-2008, 12:18 PM
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Default RE: jeet longer stroke

You would have to ask Dave Shadel or one of the Nelson pilots about that. I have not set up or flown one of the Nelson LS engines myself, so I could not comment on their setup.

My experience...

I only use the head shims to affect engine performance. And I only do any adjustment there if the air temperature is very, very warm. My best Q-500 engine has not been taken apart since Dub sent it to me and it runs like a watch.

Moving the sleeve .010" or .015" or so with a shim does not change the timing to the point where it will affect performance. The only reason I have used liner shims is to establish a correct piston deck height - to compensate for tolerances in the sleeve/case/rod. That is rarely required because the parts Dub produces are pretty much right on nominal dimensions.
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Old 09-19-2008, 01:25 PM
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Default RE: jeet longer stroke

WHEN I FLY AND DOWN GLOW PLUG IT IS BLACK AND PISTON

WHAT DO I NEED DO?
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