On my 85 I havig this problem where if i barely open the throttle, or want to keep a constant speed, it spudders real bad. If i open the throttle up its very smooth and has alot of power, but sitll on a soft throttle it spudders, like when im on the highway and want to keep a speed of say 80 mph, i cant, it spudders bad and i gotta keep opening the throttle and speeding up. I removed my rats nest after searching relentlessly for a vacuum leak, thought that would help, and it accually did help a Little bit on the spudder, but really nothing. I did gain a noticeable amount of power, but i just cant figure this out. It really pisses me off when im trying to conserv gas and i gotta keep opening the throttle because it spudders so bad when i try to press the accelerator barely. I have the nikki carb, 95,000 miles, straight piped and rb headers. car is in almost perfect shape besides this spuddering. What could be a common problem that causes this? I got a new fuel filter just a month ago too.

 

I also forgot to ad that i cant get it to idle under 1400 rpm, and the RPM gauge will sparaticly jump from what seems to be 1000-2000 rpm while idling, when the motor really isnt..

Thanks so much for any help! im going crazy here.

 

Check timing maybe. Also have you adjusted the carb at all? Did this start suddenly or did it take a while to get this bad?

 

the only thing i did to the carb was removed the spring on the right to have secondaries kick in sooner. And when i did that i didnt have this problem, came out of no where

 

sounds like vacuum leak to me....that would make it idle high and sputter.

 

i've gone around with my carb spray and checked for leaks, there are aren't any as far as i can tell, and everything left open from the rats nest removable has been plugged.

 

yep ... still sounds like a vacuum leak ...
check the back of the intake manifold - behind the secondary runner for number 2 (towards the transmission) and see if it's leaking from there. it happened once to me - i don't know what that's called back there, but it can cause everything that you described.

hope that helps ...

 

Vacuum leak.

 

Take a piece of rubber hose and hold one end to your ear. Use the other end to listen around your motor, like a stethoscope. You will be able to clearly hear a vacuum leak, any bad bearings (like alternator), or the farts of any mice hiding in your garage. Good luck....

By the way, have you replaced your fuel filter lately?