I have a 1971 240Z I just picked up all original stock. I was messin with the adjustments underneath the carbs and now I cant get it to work right. When its cold it will run good then when you rev up engine and it warms up it just starts to die like its not getting any fuel or like its running on one cylinder. I turned dials clockwise from top all the way in then 3 turns back out on both sides and now it wont run right..I was trying to tune it richer or leaner but now I cant do anything with it. any help appreciated.

ShredZ

 

Do you have a Haynes Manual? I am planning to work with my SUs for the first time this week, so I am not an expert. From my understanding of the book- turn both adjustments UP (Clockwise) until they stop. Back each off (counter clockwise 1 full turn (360 degrees). With engine running turn each adjustment (Front and rear) 1/8 turn clockwise and check for smooth idle. Repeat this in 1/8 increments until you determine the smoothest, fastest idling speed.
These adjustments are based on BALANCED air flow, so you may need to make sure they are syncronized first. Get the book or take it to an expert. Good Luck. Let me know how you do.

 

I ordered the Z therapy video maybe that will get me back on track.

To the anonymous poster, Yes I know how many turns I put it back and now it doesnt run right. seems like something just went bad like maybe timing or something.

 

where is the post by NORM on the 12.9s SU's I'd like to read it. I want to see how he tuned his carbs

 

The ZTherapy video should get you on the right track - it's very good. You may want to pick up a flow meter - MSA sells them - since the balance between the two carbs is very important for smooth running. SU's are no mystery once you understand how they work.

 

Thanks guys I will post how I make out

 

Thanks Amber, that was really cool I have three sets of carbs 2 early 4 screw and 1 dual downdraft webers. I like the SU's. I'm waiting till I have the extra cash to send out for the Ztherapy kit. I just got my Suspension Tech bars in today 1"f and 7/8"r. I'll put them in tomarrow, and probably play with my carbs to. We've had 4 days of sun here in Washington so I'm taking full advantage of it. I'm getting new tire's tomarrow too, wider is better.

 

Amber, I just put the carbs I rebuilt on and pulled the others off. The old one I had tuned perfectly finally. The new ones I can't seem to get to operate well though. The rear one is adjusted fine the front one just won't keep up and sound like it is missing. I pulled the plugs cleaned them up a bit and put them back in ran o.k. but from about 4500rpm and beyond, they still miss. I both of them idleing smooth. It's starting to drive me nuts. I think i'm gonna put the front one from the others on after I rebuild it tonite. So if you have any suggestions give a shout. I'll have it all smooth again tonite, I hope. At least I can still get to work tomarrow night.

What turns? There all straight to my Z

 

Got those little suckers to tune up right a couple days ago. I was just driving to work (2 left turns and a right) so it;s not very far. They were fine full throttle 1st 2nd mid 3rd 4500rpm started to choke a bit, riched them up a bit and no choke. So they run good now. My fuel econ sucks though so I still need some tuning. I decided to punk out and go the easy route, no not have shop do it. I bought this kit called colortune. Adjust till you see blue w/ a little tiny bit of orange I found out for power, just a nice blue for econ. So all my probs solved for $45

What turns? There all straight to my Z

 

Just wanted to let you know what the problem with my SU's were. My gas tank was rusty and crap was getting in the lines so it has been replaced by gastankrenu and works great now.
Except I have one question. One of the carbs piston doesnt raise as high as the other when giving it gas. What could be problem?

ShredZ