Volvo 3.0L carb adjustment questions

[cmartin]

Hi everyone. First off, I can't thank you experts out there enough. Hopefully your generosity of time and knowledge is paid back to you someday.

I'm going to do a full engine tune-up on our 05' Volvo 3.0L i/o as soon as my seloc manual arrives. I was just trying to learn my way around the carb today and I was a bit confused. First off, I had trouble finding the idle mix screw. I expected it to be mounted on the outside housing. Is it the one in the middle of the photo below?

Next, I was REALLY confused by how little difference there was between the idle and WOT shifter position. See the two photos below.

The throttle plate seemed to hardly move. To take these pictures, I disengaged the gearshift mechanism with the button on the throttle and took one pic with the throttle all the way forward and the other one with it straight up.

Is this minor difference in throttle plate position common or ok? I expected WOT to be literally wide open and idle to be basically closed.

Also, are the deposits on the throttle plate normal for a carb or should I plan on taking it apart and cleaning it?

Thanks as always and happy 4th. Chris.

 

[Don S]

Re: Volvo 3.0L carb adjustment questions

There are 2 idle mixture screws on a Holley carb, one on each side of the block in front of the float chamber. Being a 2005, they probably have seals over them so you can't mess with them.
That thing you are calling a throttle plate, is actually the choke plate. There are 2 throttle plates inside the carb. Open the choke, and you can see them in the lower part of the carb.

That screw you are looking at in the first picture is the screw that attaches the accelerator pump nozzle.

You really need to get the OEM service manual for your engine and drive, not the Seloc's, very little usable information in them.

 

[dallasag]

Re: Volvo 3.0L carb adjustment questions

Sorry to bump an old thread but it has some pictures and info helpful to my question.

I have a 2005 Volvo 4.3 and believe that I need to adjust the idle mixture screws to correct a rough engine after reducing the idle speed screw (to reduce idle rpm).

The service manual states:

3.0GL-B, 4.3GL-C, 5.0GL-D, 5.7GL-D and later models
comply with California Air Resouce Board (CARB) emission
standards. If the engine will be used in California, the
idle mixture screw covers must not be removed. If the covers
are removed, the metering block must be replaced
before operating in California.

Don also made a comment above about the screws being sealed but did not state what your options were with sealed idle mixture screws. I am in Texas, not CA.

I can't seem to find the idle mixture screws and the service manual gives me no helpful pictures. Are they sealed? Can I adjust them? Where are they at?

Thanks in advance for your help.

 

[dallasag]

Re: Volvo 3.0L carb adjustment questions

ttt

 

[dallasag]

Re: Volvo 3.0L carb adjustment questions

Anyone...anyone...