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Old 02-22-2004, 10:20 AM   #106
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Default REX P5 shim tuning

Motorman,I was wondering if you have any experience with this engine and what would be a good starting point for 1000 foot elevation ,high humidity,offroad. It currently has .21 head clearance and running 30% fuel.also do you have any reccomendations for break in processes as the novarossi manual is rather vague.....
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Old 02-22-2004, 11:23 AM   #107
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In case Dennis won't have an answer, you'll find lots of info here:

http://www.rc-racing.com/cgi-bin/pw/...howforgotten=2
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Old 03-01-2004, 08:34 PM   #108
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Motorman, I am new to this site and have learned a lot from this thread but I do have one question. I have an RB X12 5 port turbo in my Serpent Impulse Pro and I want to change from 20% to 30% nitro. It has the stock shim (approx. .015", I don't have a digital micrometer) and I read elswhere that you are supposed to add a .01mm (?) shim if you want to run 30%. Based upon the info here that would seem incorrect. Do you agree? I would really like to know what you think. I live in So. Fla (hot, humid and +10' above sea level). I would also like a glow plug recommendation please. I have an MT-12 I am putting in my truck and the info you gave on that was perfect.

Thanks,
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Old 03-12-2004, 07:49 AM   #109
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Default SHIMING A .21 ENGINE

MOTORMAN or anybody with experience, can you post the basic guidelines for correctly shiming a .21 engine???

Lets say an Off-Road Nova .21 based engine using 20% Nitro at sea level, what would be the ideal total chamber?? and the recommended Glow Plug??
Air temps are between 15 and 21 C and humidity around 75% to 85%.
Thanks
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Old 03-17-2004, 12:31 PM   #110
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Default Re: SHIMING A .21 ENGINE

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Originally posted by afm
MOTORMAN or anybody with experience, can you post the basic guidelines for correctly shiming a .21 engine???

Lets say an Off-Road Nova .21 based engine using 20% Nitro at sea level, what would be the ideal total chamber?? and the recommended Glow Plug??
Air temps are between 15 and 21 C and humidity around 75% to 85%.
Thanks
AFM
Anybody care to comment on above
Thanks
AFM
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Old 03-17-2004, 07:41 PM   #111
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I am planning to get a Novarossi NSR12S5 or NS15S5 engine and they both come with 0.3mm head shim (correct me if i am wrong)
I will be running 20% fuel. In that case, Do i need to add 0.1mm head shim to get proper compression?

Thanks.
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Old 03-30-2004, 01:05 AM   #112
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I just got one and the manual says 0.3mm is perfect for 0-20% nitro and 0.4mm for 20-30% so should be ok with 0.3mm
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Old 11-27-2007, 11:27 PM   #113
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Can anyone here tell me where I'd find a degree/timing wheel small enough to use on a .21? My best friend has been building some BALLISTIC engines by "making adjustments" to the port timing on his sleeves with a Dremel. I'd like to get him a timing wheel for Christmas.
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Old 11-28-2007, 06:01 AM   #114
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quick question:

if engine is losing compression, will removing shims helps to boost compression?
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Old 11-28-2007, 06:08 AM   #115
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Speed - you can buy yourself 2 protractors or print one from http://www.ossmann.com/protractor/

Keavze it can help but not for long.
Your options are to have the sleeve pinched or buy a piston/sleave set or just get another motor.

For 16% we found .35mm clearance to be ideal and .4/45mm gave a tad more rpm but lacked bottom end.
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Old 11-28-2007, 06:34 AM   #116
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Quote:
Originally Posted by razzor View Post
Keavze it can help but not for long.
Your options are to have the sleeve pinched or buy a piston/sleave set or just get another motor.
what do u mean by 'pinching' the sleeve?
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Old 11-28-2007, 08:05 AM   #117
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Pinching is expanding the piston or making the sleeve smaller for a tighter fit.
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Old 11-29-2007, 12:25 AM   #118
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Quote:
Originally Posted by Roelof View Post
Pinching is expanding the piston or making the sleeve smaller for a tighter fit.
ok but how do i do that?
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Old 11-29-2007, 12:33 AM   #119
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Check with your local racers, usually there is one or two guys that pinch sleeves. Even try the local hobby shop.

Basically its squeezing the sleeve just a bit to give the piston a better fit.
It does give just that little bit more life out of your engine and chanmging the rod would be recommended too.
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