carb adjustment question

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Feb 5, 2019
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so my 40 wants to die when i come to stops (rumbles out when the rpm lowers significantly), the lower end of the idle isnt enough to keep it on. I dont want to have to play with choke the entire time im driving just to keep it on. The car runs fine other than that. Background purposes: P.O. had installed headers and also a power steering conversion which messed with some of the hook-ups, whereby he had to maniuplate the carb for connections. So, im not sure how that affects the settings but i need more on my low end.
question is this - which screw do i turn to mess with that? fast idle screw?
 
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Maybe some additional information as to which year vehicle and which carburetor is on it. Pictures would likely help.
 
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Do what @Pighead says. But if you can’t adjust a carb you’ll need help with those too. Get yourself a set of FSMs and spend your evenings studying them. Then report back. A carb adjustment is easy but there’s more than one screw involved and timing and valves need to be spot on.
 
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You could turn up the idle speed screw (which is the one that is hard to see because it is in the cast iron base and not attached to any linkage on the stock Aisan carb). However, this is often a band aid for a larger problem of an intake manifold vacuum leak or a clogged idle fuel passage way. Turn up the idle speed and then check for vacuum leaks.

After getting the engine to “idle”, take off the air cleaner and check if you can see fuel dribbling out of the primary nozzle. If so, this is prima facie evidence for a vacuum leak / idle fuel problem.
 
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Ya no leaks … and I have all the FSM’s .. I had purchased a rebuild kit and completed that a while back. I think I’ll end up just taking the car in ValleyHybrid and ask them to figure it out. But for a band aid until then I will turn the screw.
 

Pighead

Stop calling it an FJ
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If you've completed a rebuild kit you should know where your idle speed screw is. Here's mine.
As Pin_Head said, you can't see it. I feel around for it. I know where it is 'cause I've completed a rebuild kit or two.

20220523_133035.jpg
 
Joined
Feb 5, 2019
Messages
777
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If you've completed a rebuild kit you should know where your idle speed screw is. Here's mine.
As Pin_Head said, you can't see it. I feel around for it. I know where it is 'cause I've completed a rebuild kit or two.

View attachment 3016535
ya, no i know which one your talking about and where it is i was just not sure if to mess with the low end idle i should mess with which screw: TP, Fast idle, or throttle...so i have my answer: fast idle screw (idle speed screw)
 
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No. Not the fast idle screw. The main idle speed adjustment in the base of the carb closest to the inside of the carb and not on any linkage component. Fast idle is part of the choke linkage. TP is different.
 

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