85 firebird stock 305. I did a top end rebuild about 8 years ago (cam, rods, gaskets, rebuild q-jet and a few other odds and ends) and the car has been sitting ever since. Still starts fine and I fire it up to make sure everything is running fine. However, when it is warm and starts to idle down it runs really rough like its about to die. Also if u slightly press the gas it will stammer and die or barely recover. I found a vacuum line on the back of the carb that goes no where. I am assuming this is the problem, but where does it go?

http://s1373.photobucket.com/user/Ti...81685.jpg.html

http://i1373.photobucket.com/albums/...ps87f70734.jpg

I put a little piece of hose and a golf tee on it to be visible in the picture.

 

Looks like the brake line bleed is attached....is the EGR vacuum line attached?

 

Never mind...I see that it is attached.

 

I have had similar issues with mine.... Does it seem like fuel starvation? Check your fuel filter at the carb .... Found out mine had the wrong filter

 

Check this link -

https://www.thirdgen.org/forums/tech...iagrams-i.html

 

This is embarassing. I should know this since I worked on an 85 not too long ago (or was it 8 years ago? I lose track of time every now and then!).

FAIRLY sure that line would go to the Thermac (intake air heating system) in the stock air cleaner assembly for that year. If you aren't running a stock air cleaner housing, you can just plug it and forget it.

 

Well thanks for the heads up, damon, that would make sense since I do not have the stock air cleaner anymore. I put a dress up kit on it with valve covers and air k&n air filter (I was 18). I guess I will check the fuel filter and those vacuum diagrams. Awesome link chuck, I will post updates

 

ok, so I re-routed my vacuum lines because they were a little out of whack and it seems to idle alot better but still bogs down under load. Could be one of a million things now I would assume. I hope its actually a piston ring so i can justify to the wife to take the motor out and rebuild it I will run a compression test, what should my compression be at for a stock 305 85 bird??

 

that varies alot depending on temp and altitude. as long as they are all within about 10-15% of each other you are good.