'78 FJ40 carb adjustment (1 Viewer)

[mumma]

I have a '78 FJ4 that is running pretty good now that I have the electrical issues sorted out. (It was the ground.)

However, now that I have been driving it around an issue has popped up. It idles too high. I've looked at some threads here, and this one in particular has been helpful forum.ih8mud.com/40-55-series-tech/538727-problems-w-76-idle-pickup.html

But when I was poking around in the engine it just didn't make sense. I can't figure out which screw does what...can someone help me out?

This is what my carb looks like - the two screws I marked - what do they do?

If I want to lower the idle (when it is all warmed up and humming along) which screw gets turned?

 

[mumma]

The picture is sideways...

Here is a link to the thread that was somewhat helpful

https://forum.ih8mud.com/40-55-series-tech/538727-problems-w-76-idle-pickup.html

 

[91 4runner]

before you go playing with the carb adjustments be sure there are no vacuum leaks, the valves are adjusted and the timing is correct, after all of that has been accomplished use the "Lean Drop" method for tuning the idle circuit.

 

[Pin_Head]

The idle speed screw goes through the cast iron base and is not one of the two screws you have boxed, which are the throttle positioner speed and full choke speed screws. The idle speed screw is hard to see and most people miss it.

 

[mumma]

Ok - check for vacuum leaks then check timing then mess with carb adjustment. Got it.

Just for future reference...red box is throttle positioner speed screw and yellow box is the full choke speed screw? Or do I have that mixed up?

Is the idle speed screw even in the picture?

Thanks for your replies.

 

[edwjmcgrath]

The idle speed screw is on the back (firewall) side of the carb and it is vertical, not horizontal. It is really hard to find, but after you've adjusted your idle 30-40 times, you'll be able to find it with your eyes closed.
Here are a couple of pics to help you find it.
https://forum.ih8mud.com/40-55-series-tech/624433-77-2f-idle-speed-screw.html

 

[chuckost]

Is it smogged for cal? I have a 78 40 and couldn't get it to change idle until I found out the speed sensor on top of the tranny was disconnected.