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Old 03-31-2005, 03:43 PM   #1
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Default 30% nitro to 20%, any advise

Hi
I bought two used engines from a person who was running them with 30% nitro, in my club the max percentage of nitro allowed is 20%.
Any reccomenations on what to watch out for, different needle settings, shims?
Thanks
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Old 04-01-2005, 09:11 PM   #2
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JLMG,
When I dropped from 30% to 20% I went with a slightly hotter glow plug. Depending on how experienced the person you bought the engines from was at tuning, you might have to remove a head shim(probably won't have to). As far as needle setting your on your own, there are to many variables that come into play for me to advise. Hope this helps alittle.
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Old 04-02-2005, 08:58 AM   #3
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yes It helps thanks
You mentioned that it may not necessary to take one shim off< how do I know if I should or should not take one shim off?
Thanks
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Old 04-02-2005, 09:06 AM   #4
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If the low end is weak that means the ignition delayed. Then you need hotter plug or higher compression to advance the ignition.
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Old 04-02-2005, 09:07 AM   #5
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JLMG,
When you take the button off and look under it there will be more than one shim, if there is you may have to remove one. It is a bit more complex than just adding or removing a shim. The main thing to look for when running 30% without adding proper head clearance is burning and pitting of the top of the piston, if the top of your piston is smooth then your in the correct ballpark. This all referrs to flashpoint and timing. I could go on for days on the subject but this is the short version. Fell free if you have any other ?'s.
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Old 04-12-2005, 09:52 PM   #6
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don't mean to hijack this thread, but I had a question about going in the opposite direction. I have a Novarossi RX21 P5 that I'm currently running 20% in. I'm planning on racing my buggy and everyone uses 30%. The motor is stock and only has about 1/2 a gallon through it. Would I need to add a head shim going up in nitro, or would it be OK the way it is now. I believe the manual said that 25% nitro was recommended. Would a nitro increase of 5% be that bif of a deal without hurting the motor?
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Old 04-12-2005, 10:04 PM   #7
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vgibbens,
You should be fine with 30% as most .21 engines are designed for that nitro content. You will probably have to retune the carb, but you will make more power.
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Old 04-12-2005, 10:06 PM   #8
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Thanks, I figured I'd have to richen it up a little. BTW, I'm switching to Sidewinder Race blend 30%.
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