OS 9B low end carb setting?

Intlwaters

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longballlumber

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For those of you that have run the OS 9B carb in your scales…. What is the ball park setting for the low end needle?

Thanks,
Mike
 

FloridaScaleBoater

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Evening Mike,
Don't know how others do this, but many years ago, Jack StClair shared this with me.
Open carb to WOT, adjust low speed needle til it touches a #49 drill bit between LSN & spray bar
(Works out to .073")
When its right, the #49 drill bit will drag slightly between the spray bar & the end of the low speed needle.
 

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Don Ferrette

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Evening Mike,
Don't know how others do this, but many years ago, Jack StClair shared this with me.
Open carb to WOT, adjust low speed needle til it touches a #49 drill bit between LSN & spray bar
(Works out to .073")
When its right, the #49 drill bit will drag slightly between the spray bar & the end of the low speed needle.
Yup, that'll get you really close.
 

Mike Cathey

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A general rule of thumb when setting low speed needles is if at idle the motor slowly bogs down and dies it's too rich. If at idle the motor picks up RPM it's too lean. I think it's easier to tune from rich to lean. I keep leaning until when I snap the throttle open there's no hesitation.

On the OS9B a hex head bit with the correct size blade screwdriver bit and with a small, course Dremel sanding drum pushed over the shank is an easy way to adjust the low-speed needle.
 

FloridaScaleBoater

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A general rule of thumb when setting low speed needles is if at idle the motor slowly bogs down and dies it's too rich. If at idle the motor picks up RPM it's too lean. I think it's easier to tune from rich to lean. I keep leaning until when I snap the throttle open there's no hesitation.

On the OS9B a hex head bit with the correct size blade screwdriver bit and with a small, course Dremel sanding drum pushed over the shank is an easy way to adjust the low-speed needle.
I like that bit/drum sander trick!!
 
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