78 280z idle problem

[s14280zx]

A while back I was having problems with idle and acceleration with my 78 280z. You guys gave me alot of helpful advice, and I managed to get it running really good.(It turned out to be the throttle pos. switch. I took the cover off, and bent the left contact slightly so it made contact right away, and it solved the hesitation problem.) The only problem I have now is when I come to a redlight, or push the clutch in, if the idling is above 1500 rpm, the idle will slowly climb to 3000 rpm. If I wait until the rpm's go down to about 1200, and then push the clutch in, it will stay around 1000 rpm. I checked the linkage and throttle body, and it is closed. When I start it up it idles fine. Any help is appreciated. THANKS

[sblake01]

We talked a little about that problem here:

http://www.classiczcars.com/forums/showthread.php?t=27914&highlight=BCDD

[s14280zx]

Thanks, I'll give that a try, if I have to, I can take one off of my zx parts cars. I'll see if I can adjust it first. Thanks for the help.

[s14280zx]

I was looking at my bcdd, and I felt around on the bottom, and all I could feel is two small screws that I think are phillips (I can't see in too good). Are those the ones I need to loosen. If not,how do I get the bcdd to turn? THANKS

[s14280zx]

I tried adjusting the bcdd both ways, and got it a little better, but it still does the same thing. I have a broken bolt on my exhaust manifold(rear top one at the head. Could a vacuum leak cause this? I pulled a vacuum hose from the intake manifold, and the idle went up. I am also getting a pretty bad exhaust smell in the car when the window is down.( too rich?)Any suggestions would be appreciated.