I have a 1984 firebird SE with a 2.8 engine. The exhaust pipe is really sooty of black and it dieasles after I shut it off. Where are the idle mixture screws? I've looked everywhere.

 

When my carbed 2.8 developed a deiseling problem, I found the problem to be a rotted hose for the vacuum advance.

 

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isn't deiseling after you shut the motor off caused by a hotspot?
this way when you shut the car off which will cut the spark something inside the motor will still be hot enough to ignite the airfuel mixture

I know my celica did that and came to be a cooling issue. fixed the cooling and the car quit.

now my mav does it also though I think it has something to do with the plugs running too hot mixed with a cooling issue


as for the soot in the exhaust might be more then just idle mixture. sure it might help but you must be running rich through the rest the powerband also.when was the last time a full tuneup was done?

 

Ok, let me ask this. . .Where are the idle mixture screws. Thanks.

 

Whenever I use anything less than 89 octane fuel my Camaro diesels.

 

WHERE ARE THE IDLE MIXTURE SCREWS?

 

I'll be honest,
On my S-10 Blazer, it ALWAYS dieseled on shut off. NOT EVERY TIME, but, always.
Since I played with the distributor. I installed Accel advance springs.
I'm looking now for the carb screw.
HAVE YOU REBUILT THE CARB?
Is the throttle plate re-bushed?
It's is where I thought, on the throttle plate, front.
YOU NEED A SPECIAL "D" SHAPED FEMALE SOCKET to adjust.
I bought one.
Long flex stem.
ABout $20-ish.
IS the electronic Solenoid connected to your car?
THAT ALSO CONTROLS the dieseling BIG TIME, TOO! Promise.
Mine is gone, was "left off" by first Chevy dealer rebuild!
Honsest tips from one that has what ya got (85 S-10 Blazer, 49 state Version), since 1989. Now with 211,500 miles on it.
New to truck, tranny & MPFI short block with old induction system coming soon!

 

WHERE ARE THE IDLE MIXTURE SCREWS?????????

 

I'm going out to my truck, to look to help ya.
BUT, it's in the throttle base plate, you access, thru a passage, using this "D" shaped socket tool to adjust.
Cold out here in the CA hills.
In the front of your carb, you have a Choke Pot and several vacuum lines/hoses.
IN THE THROTTLE BASE PLATE, you'll see a "SCREW-D SHAPED".
That's it.
It protrudes ever so slightly, kinda like a cute girls' nipple
Go get a vacuum gauge and set your idle.
Good luck.
If your throttle plate is worn, (mine was big time!), only a proper rebuild will cure that problem.
Hope this helps ya.
Really, go get the tool.
OR drive it to a smog test place and have them, set it up for ya, by the probe they use for testing.
That's the easiest! Only $20 or so, I'll bet.
When it's set right, it drives great!

 

Karl,
Thanks but I think you're talking about idle screw. I'm talking the fuel mixture screws to adjust the fuel air ratio. I don't want to adjust the idle, I want to adjust the fuel air mixture. Thanks Karl.

 

I truly believe that's it.
I recall adjusting it, there, with my tool I bought, smog station, test probe and watching results on the monitor.
Idle speed on side, throttle.
Everything else is adjusted internally, then buttoned up.
Go to a parts store, break the seal on a Chiltons, etc and look at the pics & text. S-10, & F Bodies only read.
Or cheat and have it done, like I did.
I paid next to nothing for not having to guess & he let me do the adjustment on his stuff. I paid him for the smog test.
And I pass and it ran real good, too.
How much new stuff have you installed?
I mean choke pots, vacuum lines, rebuilt this & that?
The choke pots go for $40 a piece, FYI.

 

Karl, thanks man. Actually, I'm kind of a *****. I just took the A.I.R ssystem off my car and bought the correct Fbody CC carb. THe carb on there is a S10 one (like we talked about a month ago or soemthing). I'm just worried that with the CC carb it won't work. I'm also pussed out about all the hose and wiring hook ups. I've never done this before. That's why I was wondering if there was an screw to lean out the mixture. ANyways, need help taking off the s10 carb and putting on the cc one. Just build my confidence in myself. Thanks again Karl. I'm 17 and just read books. But the whole carb this is scary.

Thanks again Karl,
Jon

 

Here's how I did mine.
I just blocked off (plugged up) all I could.
I inserted a plug into several "holes" on the intake (of my S-10 example). It runs, but, my oil pump is shot and my block is dead. I was lucky to make it move, for ease of my family relocation.
But in the end, my engine work was wasted.
Not the carb/distributor rebuild. That turned out primo.
Just plug off all you can/should.
Get it to run smooth then add back the varible (smog/hoses & stuff) REPLACE cracked lines as needed.
You do need a book/guide for the hoses.
Keep searching.
Sorry I couldn't give ya better answer, wish I could be there to guide ya better.