What is this Carb Guru's!?!?

[J_Carter]

Ok, I have a 1993 140 hp Evinrude V4, 90? Looper Engine S/N# E140TXETF that I am rebuilding the carbs on. After rebuilding everything by the book...it hit me that it never mentioned anything about the needle valve. I thought, dern I've cleaned everything else I have to at least pull one out and check it...sure enough it was rusted where it meets the channels that lead to it. Cleaned the rust off and it was actually pitted a little.

Now for the pics and questions...

Schematic of the carb...(don't know why the bottom is gone...#9 is the needle valve)


Here are the 4 Carbs


At the tip of my index finger is where the needle valve/spring came out of...


Here is the Needle Valve after I took it out...note the rust around it...


Now for the questions
1) What exactly does this needle do? (I'm thinking air/fuel mixture)
2) How do you set it back to the correct depth? (I was going to measure down to the other three with calipers and put it back there)
3) Why didn't the book mention anything about cleaning it?
4) These are the only screws that are accessible on the carbs while the air silencer is still installed. What are the proper adjustment procedures?
5) Are these mainly for elevation change adjustments once you get them dialed in?

Thank You all!!!

 

[seahorse5]

Re: What is this Carb Guru's!?!?

That is the idle air bleed adjustment needle. It works backwards compared to an fuel adjustment screw. As you turn it inwards, the idle richens up.

In good shape, most engines would run well when it is between 1-1/2 snf 2-1/2 turns open. On some well worn engines you may have to run it almost closed.

 

[J_Carter]

Re: What is this Carb Guru's!?!?

Thanks for the reply!! Should I be concerned about the pits that the "rust" left on it? I was planning on getting new needles for all 4 after I seen the one like it was. Don't know if that's really needed though. I'm just trying to do everything perfect while I'm in there.

Also, I'm unhooking my VRO 2 pump while it's easily accessible. As well as rebuilding the fuel side of it. Any other things I should check/ do while I'm in it?