tuning for a new header?

[palauoriginal]

so I installed my header today and went for a drive i noticed that the car idles really low now. at around 550-650rpm. something like that. i tried the idle adjustment screw but it didnt bring it back to the 800rpm range. i was wondering what i could do to try and correct this. also this was with no exhaust just the header. im getting an exhaust on tuesday so would this help with the rpm problem?. thanks in advance.

this is on the stock FI btw.

[red_dog007]

Could be because you have no exhaust. How far does the exhaust go down or do you not have any system installed period?

Your compression is probably lower then what it is supposed to be at, so idle will run a little rough and lower to.

[Arne]

More details might help too, like what year and model Z you are working on?

[palauoriginal]

i have no exhaust right now just the header. oh and its a 1975.