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Old 04-13-2005, 08:57 AM   #1591
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Quote:
Originally posted by Surge
Just thought I'd suggest it. Markp27's problem sounded either like a plug or a head shim. I've been running .4mm shims in my Rex with 3rd generation BRB and last weekend on my small local track tried .5mm and it worked maybe a little better. I suggest you try it and see what happens.
1st, 2nd and 3rd generation... How do I go about indentifying them?
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Old 04-13-2005, 09:01 AM   #1592
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Quote:
Originally posted by InitialD
1st, 2nd and 3rd generation... How do I go about indentifying them?
When did you get them?
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Old 04-13-2005, 09:14 AM   #1593
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i am even more confused now......


Quote:
Originally posted by Palmaris Europe
There seems to be a lot of confusion regarding shimming and head clearance etc...

Shims are not dictated according to Nitro content, plug or weather conditions etc... Shims are set according to the amount of crankpin/conrod play, wristpin/conrod play, big end bearing play and how tight the P/S fit are.

The key is to find the correct shimming that produces the most power and torque from the engine. The closer you can get the head clearance, the more power and torque the engine will produce.

Many people declare that adding a shim is the correct thing to do when getting pre-detonation or blowing plugs but all they are actually doing is reducing the amount of usable power the engine can produce within its designated powerband. This then means you have to lean the engine out further to regain that lost power which puts the engine under increased stress.

Instead you should aim for a clearance that produces the most power and torque and keep the engine at this at all times. If pre-detonation or post-detonation occurs you should remedy this by increasing the squish area with that clearance to maintain the correct compression ratio. (making the squish area wider or narrower).

This will stop wrong detonation timing but keep the same power/torque level as was previously had. the engine will happily run that bit richer while still maintaining the desired punch from corners and pulling bigger gears.
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Old 04-13-2005, 09:21 AM   #1594
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Quote:
Originally posted by Data
i am even more confused now......
Its easier for the manufacturers etc to say add a shim or remove a shim depending on whether the engine is getting predetonation etc. hence why everyone now takes it for granted that this is the proper thing to do.
The biggest problem is that when you do it the proper way you could end up using a different head buttons at a given track each weekend which would soon add up on cost. It gives the manufacturers headaches by having to design many different head buttons also.
What the manufacturers fail to mention is that adding a shim also takes away power and torque from the engine which the racer doesnt want to hear.
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Old 04-13-2005, 09:43 AM   #1595
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Quote:
Originally posted by Palmaris Europe
What the manufacturers fail to mention is that adding a shim also takes away power and torque from the engine which the racer doesnt want to hear.
could you define "power and troque" ? what do you mean exactly when you say "power and troque" ?
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Old 04-13-2005, 09:50 AM   #1596
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Quote:
Originally posted by Data
could you define "power and troque" ? what do you mean exactly when you say "power and troque" ?
more power = faster top end speed for a given gear ratio

torque - how well the car launches and accelerates out of corners or from standing still.
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Old 04-13-2005, 09:59 AM   #1597
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Quote:
Originally posted by Palmaris Europe
more power = faster top end speed for a given gear ratio

torque - how well the car launches and accelerates out of corners or from standing still.
thanks for the definitions

so which major factor do you think will contribute to the HP and which to the torque ?
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Old 04-13-2005, 10:14 AM   #1598
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Quote:
Originally posted by Palmaris Europe
Narrowing is not actually possible in a safe way. By wider or narrow I mean making the dome in the button wider or narrower.
To get it narrower you would need to know the exact area required and get a button made to suit. Just a matter of removing material from the appropriate place on an existing button to get it bigger.

I dont advise anyone to go try doing this unless they know exactly what they are doing and can make the proper calculations and changes to get the desired effect.
since maybe only a few of us has the expertise/skill to do the calculations and the equipments/resources to make the head button, what would you suggest for the rest of us do ?
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Old 04-13-2005, 10:25 AM   #1599
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Hi guys.
Please let me clearify some issues about head shimming.
First of all, it is depend a lot if you running legal or outlaw carbs and pipes-it makes huge difference, second is ambient temperature, pressure and humidity.
For people who is running outlaw version (carb 6mm+ and pipe 6mm+), for fuel 30% I will start with 0.5 mm shimming. For whom who is running legal carbs and pipes and 30 % fuel I will start with 0.3-0.4 mm., for whom who is running 16% and legal-it should be 0.3 mm.
The higher altitude over the see level, I will go to add 0.1mm shims.
Here is another situation is happening-people star running and found that after initial tunning is done and motor generate very good power, then when the car come to the pit it is ideling too high. In most cases happened to be that people are start reaching needles. I will suggest first to drop idle by unscrew idle screw. Due to the difference in materials set ups (long way to go to explain), engine is generating much more power (mostly on RPM of it side) with the same carb opening at idle-so according to this, carb needs to be close further to bring RPM down, but not reaching it.
One more thing-set can easy survive at 300 F, but this is not the best running temp for long runs. We do test our set at 325F for 4-5 tanks in row for durability. The best running temp is somewhere 230-260 F (depend of ambient).
In generally speaking-our sets are running leaner at bottom end and richer on top to compare original sets.
You still can run settings suggested by OEM, but definitely much more power will come up with leaner bottom and richer on top.
Please, if anybody has further questions-you are welcome to ask and will try to do my best to answer on them.
Edward
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Old 04-13-2005, 10:27 AM   #1600
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Default Re: Re: Re: Squish area

Quote:
Originally posted by Data
since maybe only a few of us has the expertise/skill to do the calculations and the equipments/resources to make the head button, what would you suggest for the rest of us do ?
I do have heve head buttons if you need, just see me at CP
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Old 04-13-2005, 10:38 AM   #1601
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Default Re: Re: Re: Re: Squish area

Quote:
Originally posted by Top Gun 777
I do have heve head buttons if you need, just see me at CP
but you go to CP mostly on sunday.....
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Old 04-13-2005, 10:46 AM   #1602
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hi edward,
at my home track the temp is in the moment around 15c, i have shimmed the engine to 0.3mm headclearence and run with a 6tc plug. the temp is around 100C on the topfin from the head. (spy test)
i set the engine like a original, what i read i must change to the brb set with leaner bottom and richer top
dieter
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Old 04-13-2005, 10:55 AM   #1603
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I suggest you try the leaner bottom end/richer top end setting. I saw a BRB engine tuned like a normal Nova engine and the engine was not near as fast as when retuned Edwards way. I think the bottom end needle was at least a turn leaner Edwards way than the other way. That's just an example. It may not be the same for every engine, so start 1/2 leaner then move slowly from there.
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Old 04-13-2005, 11:06 AM   #1604
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Default Re: Re: Re: Re: Re: Squish area

Quote:
Originally posted by Data
but you go to CP mostly on sunday.....
I was there last Saturday from 8 Am till 3 PM-you saw me there, we even chat little bit.
If you can come down any day of week during the lunch time break-I can be there, I work just 3 minuts away from there.
Just let me know and I will be there.
Edward
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Old 04-13-2005, 11:08 AM   #1605
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if you add a .1mm shim to the .3mm shim running with 30% will that give you more top end?
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