Carb idle adjustment help

I have a 1982 Cobalt with an OMC 305 GM motor with a 4bbl carb. The poor thing sit idle for almost 3 years before I got it. I drained the old gas, changed out the points, plugs, plug wires, condensor and distributor. I changed the engine oil and the lower unit oil as well as added a bunch of seafoam.

Bottom line is the boat runs awesome now, except for one small problem. I can't seem to get the idle adjusted properly. It seems to stay around 1100 when the manual calls for it to be between 550 and 600. This is not a huge problem except when I go to put it in gear. Shifting is a bit klunky. I am concerned that I will damage the tranmission if I don't get it adjusted properly.

I have played around with the idle set screw but can't seem to get it down below that 1100 mark without causing it to spit and sputter.

As the manual suggests, I have tried to adjust the two pins (needles) on the carb. However, I don't think I am doing something right. Can anyone give me hand on the best/easiest way to adjust the idle down to where it needs to be?

Thanks,

Tony

Re: Carb idle adjustment help

try removing the linkage and there is a thread on the end of it. just turn it in a bit. also there is a set sqrew that can be adjusted. You want your idle to be exact because there is a shift interuptor (on mine anyway) I hope this helps, I saw nobody replied and this just had this happen to me.

Re: Carb idle adjustment help

TFrazier said:

I am concerned that I will damage the tranmission if I don't get it adjusted properly.

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It will definately cause damage if you continue to shift into gear at 1000-1100

TFrazier said:

I have played around with the idle set screw but can't seem to get it down below that 1100 mark without causing it to spit and sputter...

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You probably need to remove the carb and do a complete rebuild. The idle circuits are probably clogged, which is why it won't run below 1000 RPM. I don't know what carb you have, but a rebuild kit shouldn't be very expensive.

An hour or two to tear it all apart, keep all of the parts neat and organized. let the carb body soak overnight. use compressed air(the canned stuff from radio shack will work) to blow out all of the passages. assemble everything, reinstall it.

THEN

You can adjust idle mixture, idle speed and choke.

Re: Carb idle adjustment help

Thanks for the advice. The carb. is a Rochester 4bbl. I'll look into the rebuild kit. Can I get this through NAPA or is there something special about it since it is on a boat.

Re: Carb idle adjustment help

I don't what differences there are in the "soft parts" between marine and automotive rochesters, but NAPA carries marine parts and can get you what you need.