carburetor impossible to adjust.....

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May 25, 2019
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54
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Prospect Ky
I am trying to adjust carb by the lean drop method. I set the idle mix screw to 1 1/2 turns and tried to get idle off 1200 rps's. with the idle screw. It wouldn't move anything. Simply couldn't get the idle to 690 to start the adjustment process. Any ideas? Original Aisan carb on an F2 engine. Thanks
 

Dizzy

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Feb 5, 2018
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Santa Fe, New Mexico
It is primarily the idle speed screw that controls engine rpm. It is on the firewall side, kinda low, the screw head faces the fender side. The idle mix screw just adjust the idle circuit mix of fuel and air.
 
Joined
May 25, 2019
Messages
54
Location
Prospect Ky
What is your vacuum reading?
haven't done that yet. need to get vac guage. also timing although it used to be correct before I adjusted the valves.....Also, Pinhead said start at 3 turns out. Going to check throttle screw today first...... thanks for the suggestions
 

1978FJ40project

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May 18, 2020
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california
Question - I need to set my idle as well. So by “3” turns out , does that mean I crank it all the way down and Then do 3 turns out ?
 
Last edited:
Joined
May 25, 2019
Messages
54
Location
Prospect Ky
Question - I need to set my idle as well. So by “3” turns out , does that mean I crank it all the way down and Then do 3 turns out ?
the 3 turns out is after fully closing the Fuel Mix screw, not idle screw. That's down low on the fender side. There is a very good video on you tube on how to adjust an aisan carb on an F2 Toyota engine
 

thebigredrocker

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Nov 6, 2013
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3,392
 
Yeah, you'll gouge the idle mix tip if you crank it down to far. Seen a few mucked up tips posted on mud.
EF463220-BA46-4C1B-A9BD-2AC3EE3DB170.jpeg

Green = throttle positioner screw. Remove & discard
Black = hi-idle screw. Adjust so idle speed goes up to around 1800RPm w/ choke knob pulled on warm engine.
Red = idle speed screw. Set to user preference, usu in the 500-700RPM range when warm.
Yellow= idle mix screw. Set 4 turns out for inital running, then screw in til RPM starts to drop, then back out til idle reaches highest speed.
 
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