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Old 02-24-2013, 10:57 AM   #43
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A couple observations about the 67mm CFM TB I just installed. Very nice piece of kit! The stock TB is 63mm...but has a VERY thick blade designed to restrict the airflow during light throttle. Of course the larger piece gives a LOT more air with much less throttle movement and make sure you set the TPS properly. The idle speed will stay under computer control with quite a bit of adjustment so turning the stop screw is really just adjusting the TPS as the computer looks for the lowest value and uses that for calibration.

Another stock TB would over-center at WOT, meaning it closed back down a little. This is NOT good! The new CFM would do this a throttle stop was fashioned to stop it at 100% open. Check when you install the TB to make sure yours doesn't open past perpendicular.

My gas mileage actually increased a bit with the CFM TB! Reason is the throttle opening is less during cruise which keeps the timing up via the reduced TPS signal.
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