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Old 09-07-2007, 11:41 AM   #1
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Default c6bbt7 head shiming

How many people have shimmed the bbt .1mm on the head? reason i ask is the manual say use 25 percent only inless u put a .1mm shim on the head, but i also know of 2 people that run 30 percent in theres and didnt shim it .1mm more.. does anyone else run it with out the .1mm shim?
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Old 09-07-2007, 01:11 PM   #2
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Most guys at my local track don't, but I have 2 c6BB7T's and in both I added the extra shim for 30%. Both of my engines run like a charm. Rody Roem on the rb boards claims the extra shim makes engine less likely to flame out and be easier to tune with the extra shim. Other people in my track argue incessantly that the shim makes no difference. You decide...
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Old 09-07-2007, 01:59 PM   #3
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im kinda agreeing with rody. you know hes no dummy on that so i will add another shim wounder if ther ecan be a fuel gain by doing this? i would think so less compression nets better fuel since u can lean the needle a little bit more... thanks for the help man...
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Old 09-07-2007, 04:12 PM   #4
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You add a .1mm shim if you are at sea level and running 30%. You shim for the nitro percentage and altitude one is at. I did it with both my WS7II and C6BB. I started with the added shim in the C6BB and added it to my WS7II later, and noticed that my WS7II was running better after that. Not necessarily faster, but just more predictable. BTW I am VERY close to sea level at my local track.
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Old 09-07-2007, 05:09 PM   #5
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well im in ky and i think that where about 350 above sea level so i was told wich i thought it was like 700 above sea level...
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Old 09-07-2007, 05:37 PM   #6
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Quote:
Originally Posted by Ultraspeed84 View Post
well im in ky and i think that where about 350 above sea level so i was told wich i thought it was like 700 above sea level...
Let me translate: "Well, I'm in KY and I think that we're about 350ft above sea level, so I was told. I thought I was at 700ft above sea level."

Sorry, bad grammar and spelling really irks me, it makes most of the people on these forums look like they haven't passed high school. It's also quite hard to read if you don't get my point.
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Old 09-08-2007, 08:24 AM   #7
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Shimming higher will make the motor run more stable through different tuning.
General rule is .024 - .027 for 30%. You can run it higher to get more stable tune and soften the motor a bit. I would not go over .031. FYI - every .1 mm = about .004".

Almost everyone I know should run a shim in that motor! It is wicked fast.

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