Carb adjust question

[MH9371B]

Was reading my service manual, and read that to get your idle speed right, start by turning mixture screw clockwise until it lightly seats itself. This is probably a really stupid question, but what does that mean? Turn it until it just barely begins to tighten?

 

[Brentathon]

Re: Carb adjust question

Yes, I would say to turn it (carefully!) until it just barely begins to stop turning, or "tighten".
I was planning to do this, myself, but those screws are sure small and tough to get to. And, they look like they only have flats (i.e. Not a hex or phillips, etc.)

 

[MH9371B]

Re: Carb adjust question

1995 Mercruiser 3.0LX
2BBL carb

 

[Bondo]

Re: Carb adjust question

Turn it until it just barely begins to tighten?

Ayuh,... Yes....

 

[Silvertip]

Re: Carb adjust question

Did not anyone notice his post said "to get idle SPEED" right, turn the idle "MIXTURE" -----. If that's what your manual really says then I suggest you pitch it because it is wrong. Which procedure are you doing? Setting the idle speed or the idle mixture. They are two different procedures. Lightly seated means just that. Turn the screw until it is "lightly seated" or barely stops turning. Idle speed is how fast (RPM) the engine is running at idle. Idle mixture adjusts the fuel/air mix to allow proper idle.

 

[fat fanny]

Re: Carb adjust question

I have the same set as you and if you have only one air idle mixture screw you have a Mercarb and the best way I have found to do this adj, is to use the smallest screwdriver you have so as not to be fouled by the length of the handle and using too much torque. And as mentioned above turn it lightly until it just about stops and turn it back out 1 1/4 turn to start and then play it by ear from there. The 1 1/4 is just a starting point for reference.

 

[MH9371B]

Re: Carb adjust question

Thanks guys, I figured it out.

She's still surging a bit at idle, but nowhere near as bad as before.

 

[killerjeep01]

Re: Carb adjust question

If its surging, its to lean, could be a gasket, or you need to go out with the mixture screw.

 

[killerjeep01]

Re: Carb adjust question

If its still surging, doesnt that mean its lean. Could be sucking air through a seal, or just needs a little more on the mixture screw.