240z running oh, so rough!

toopy

Club Member
If the fast idle screw is backed fully off and the revs are still up, i would of thought one, or more likely both carbs are running too rich.

You should be able to unscrew it enough to stall the engine!

Also check the plunger thingy behind the fast idle screw is free to move and not limiting adjustment
 

jonbills

Membership Secretary
Site Administrator
I'd think there's an air leak behind the carbs, or the cable is snagged. Check the butterflys are closed.
 

AliK

Vehicle Dating Officer
Staff member
Club Member
Not sure if this helps ....

68f4b0651fa45dd11c1e6b6345615f3c.jpg


My two penneth sayeth it is screws "A" that need backing off until, as has been said, the butterflies close and engine stalls.

Once you are satisfied the butterflies are closed and engine stalls, adjust the fast idle screw until the car starts and idles at an acceptable speed, then adjust "A" screws until the revs just start to pick up. Then back off the fast idle screw completely and balance the carbs using screw D - keep fine tuning until happy :D
 
Last edited by a moderator:

uk66fastback

Club Member
Well, back onto this now the weekend is here. A mate of mine came over and we took the carbs off again as he wasn't sure the chokes were working at all. Of course once off, it was easy to see that on both carbs the movement of the jet downwards just wasn't happening due to them being gunked up with crud. When the choke lever was pulled, the only thing happening was the connecting rod was bowing out ...

Anyway, I could see now how the jets wound in and out, so we wound them right in, then back two turns and went from there. With the chokes now working the car started after a little bit. After some work changing the points and timing the engine etc, it runs much better and the idle was round about 1100rpm. We also went back to the original distributor cap as the new one appeared to be loose. Car started right up and ran pretty well.

However, an hour later and I needed the choke again to get it going and now the idle won't come down below 2000rpm?

We're getting there, but any pointers!?
 

toopy

Club Member
I think if the jets were gunked up, then just winding them in and back out won't be sufficient,
have em out and check theres no sh**e in there, you will also be able to see if they are scored/bent/damaged in anyway :)
 

uk66fastback

Club Member
Oh, I did clean them out, made sure all the crud was gone and that the choke operated by hand on the bench pretty efficiently ...
 
Top