A few months ago i bought an 84 2.8l v6, 5 speed manual as my first car and it's been giving me a lot of problems since. The kid who owned it before me did a lot of work on it himself and didn't really know what he was doing after all. It runs really strong and drives well but the idle is off and my mechanic told me i need to replace the carb to get it running right. I'm new to cars and parts and don't know where to look for a carb, or what type to get. I'm not looking to race or anything, just get it running good. I live in California and to m understandin some carbs aren't legal here. Also the ac system blows out air when it's set to "vent" but stops blowing out air when i switch it to "heater/defrost" which can make drivig it a bit difficult in the mornings any help is greatly appreciated, thanks!

 

that sounds like a canned response from someone who doesnt know what they are doing with carbs. there is almost nothing you can do to a carb that would require complete replacement. secondly the hvac is vacuum controlled so try plugging the vacuum line to the hvac from the engine area and see if your idle issues are related. as far as the diverter problem it self not real sure havent messed with alot but i would look it over for leaks and see what happens under there when you change positions, maybe the flap is stuck hard to say over the internet

 

Welcome to TGO!

What is the idle doing? High, low, bouncing around?

Carbs are perfectly legal in California, as long as it's the factory "Quadrajet" style carb and you have all of the emissions equipment hooked up.

The first thing you have to realize, is that if you want to keep your Thirdgen, you're going to have to learn to work on it yourself. Most shops these days won't touch a carb because they don't understand them anymore and don't want to take the time to learn.

I would start by gettig a repair manual for your car, a good Carb book that explains how it works, and then do a tuneup by replacing the distributor cap, rotor, spark plugs and spark plug wires and see where that gets you.

Now, if you do a "search" on the forum for the symptoms you're having, you should be able to find some posts with people who have had smiliar issues and how it was fixed.
Best of luck!

 

It's a V6.

 

Ok, sorry, should still be a Rochester then correct?

 

Welcome aboard!

 

rochester 2bbl

 

My mechanic said there is too much air getting into the carb and it's causing it to miss beats or something when idle. When it sits idle it makes a big "put" sort of sound every little while, often enough though to worry me a bit

 

I think your mechanic is saying its running lean. That kind of leads back to what jwfirebird was saying. You probably have a vacuum leak (unhooked vacuum hose) that is causing a lean condition. Try to get a good look at the carburetor right near the intake manifold on the front and back. There are vacuum ports there that are used to run the accessories (like the HVAC system). You might see a port that is just open to the atmosphere.

 

So when i look at the carb there should be holes that look like there is supposed to be a hose attached or something? Sorry i'm not too mechanically savy :/

 

On the carb will be multiple tubes that come out of it attached to hoses, these are "vacuum lines" that are used to run various things on the car. It will look something like this. My engine bay...

Think of your engine as a giant air pump. It sucks air in, bangs it around through the fuel ignition (turns the motor over), then blows it out the exhaust).

On the close up of the carb you can see several tubes that end abruptly, those are what the black vacuum lines connect to. You can kind of see it on the farther back pictures. If there is a crack in one or one came off, it will create a suction that the engine isn't expecting, hence the "vacuum leak". It's air the motor isn't expecting which will cause it to run poorly.

 

Okay i see what you mean. A lot of the hoses on my carb seem pretty old maybe i should just replace them all, can i just buy this hosing at autozone or maybe home depot?

 

Any Autozone, Checkers, O'Reillys, Napa etc. will have the hoses. Mostly they're cut to length.

The best way to sort a vacuum leak, is to plug off all of the ports on the carb and intake and start the motor. Then reconnect the hoses one at a time until the idle jumps or changes when the new line is connected. This will tell you where the problem hose is.

If your idle doesn't change when the carb and intake are plugged off, then your leak is either internal to the carb, or one of your intake manifold gaskets probably has a leak.

 

Okay so i just remove all the hoses from it, plug off the tubes and start it up?

 

The best way to do it is to run to AZ or whatever and grab a box of assorted vacuum caps PN 46388 at AZ is an example of what I'm talking about. The you remove each vacuum hose and plug the ports. Start the engine, if it is idling at a slower, more stable, speed start connecting the hoses 1 at a time. When the idle goes up again, you found the hose with a leak. If the idle is still wacky with the vac ports plugged, your carb base gasket or your intake gaskets are leaking. If you find out that i the case, you will be doing a little more complicated work.

 

you can do one at a time. golf tee's work pretty good if you have them laying around. and as far as replacing the tubing, its never a bad idea in a old car that came with so many vacuum tubes. its best to get the tubing specifically rated for vacuum tube though, but its relatively cheap