Merc 3.0L carb rebuild question.

[Condor1970]

Rebuilding my 2BBL Mercarb for my 1989 3.0L Merc.

I have a question about the choke spring. I know the little lever needs to generally be on the right side of the spring to make it move when it needs to. However, my choke spring has sort of squared loop on the end of it. I did not notice how it was positioned when I took it off.

So, do I just put the lever "inside" the loop?

 

[Condor1970]

~~Also, my carb has no choke unloader. There is supposed to be a little tab that unloads and opens the choke a little at full throttle. Mine doesn't have one. The directions I got with my carb rebuild kit says to set the choke at "1" lean for my carb, so I did. However, the choke is fulyl shut when cold, and will not open when full throttle is engaged.
Should I just leave it, as is?

 

[CFM56-7]

The choke actuator should be positioned inside the squared loop on the choke thermostat spring. This allows the choke thermostat spring to operate the choke plate in both directions.

The choke setting is a little more tricky. Most on here recommend that you set it so the choke plate just barely closes when cold and disregard the factory recommendation of 1 tick to the lean side. On paper this sounds great, but in reality, the ambient temperature when you make this setting becomes critical and isn't specified. On my specific application, with the choke fully closed, the engine runs extremely rich and spits out lots of black smoke until the choke opens up a bit. Last time I set the choke, it was 75 degrees out and I left a decent gap in there so it wasn't quite fully closed. She now starts up great with no over rich issues.

Like you, I also do not have a choke unloader tab on my throttle arm. Ever since I got the choke thermostat properly set, I have not had the need for it.

CFM

 

[Condor1970]

Ok, I noticed mine was also spitting out a lot of black residue out the exhaust on the back of the transom before the rebuild. Kind of ugly.

So, I decided to do as you did with yours. I rotated the choke to about 6 lean clockwise until the choke flap is open about 1/8" to permanently let some air in.

Does this sound about right?

 

[CFM56-7]

Mine is open probably just a bit farther than that when it is around 75 degrees out. Your current setting might work great for you and should be a great starting point. Only way to find out is to go fire it up. If it is over choking, just open it up a bit more.

Just remember, if you make an adjustment right after running it, reference the position of the outside of the choke thermostat rather than the choke plate as the thermostat would be much warmer than ambient and therefore more open than it would be cold.

Good luck!