1989 3.0L Mercruiser Carb. Overhaul

[daveabson]

I am trying to find the factory specs. for idle valve(needle) and fuel valve(needle) settings. The carb was overhauled and needs to be fine tuned . Anyone with information on these settings please contact me. Thank You

 

[Trent]

Re: 1989 3.0L Mercruiser Carb. Overhaul

Need to know which carb you have? Two different Mercarbs. Does it have one or two idle air adjustments?

 

[daveabson]

Re: 1989 3.0L Mercruiser Carb. Overhaul

This carb has two idle adjustment screws. I am mainly concerned with the setting of the lower screw which I believe sets the fuel mixture. This engine is definately running rich. I was hoping you knew of a relative setting, say starting from bottomed out(which I don't want to do because this is a brass needle valve). Roughly how many turns out from the full in or out position? Any other information regarding the tuning of this carb. would be greatly appreciated! Thank You. Dave.

 

[Trent]

Re: 1989 3.0L Mercruiser Carb. Overhaul

First set a 1.25 turn from full in. You will have to "tweak" it. After warm up, from the first setting keep turning it out til it runs rough and then turn in til it runs rough again and split the difference.