Won't rev Under 3000rpm

[vashonz]

New '71 240z, the previous owner decided to install carbs from a '73 (but it does have an e31), since I have an extra set from one of my '72's I swap those (along with header and 2.5 in exhaust) onto the '71, keeping the intake from the '73.

 

Now when I go to start the car it starts great, but immediately idles at 3000rpm. Runs great at 3k, revs instantly to 5000 or 6000.

 

But, i dont want it to idle at 3k

 

the only way to get it lower is to force the throttle linkage closed (much harder than what the springs do), or put my hand over the front carb.

 

any thoughts? I really wanna drive the car with the better carbs on it.

 

p.s. I did read the topic below http://www.hybridz.org/phpBB2/viewtopic.php?t=17847 but his car starts a 1000rpm then goes up to 1400rpm. Could I have a more extreme version of his problem?

[Guest Anonymous]

When you wess with multiple carbs. you have to re-syncronize the throtle plates.

 

To do this:

 

1. Disconnect the main throttle linkage going to the carbs.

2. Back off all the idle set screws.

3. Loosen all the screws holding the throttle plates to the rods.

4. Gently open and then close each plate and tighten respective screw.

5. Operate carb linkage by hand and see that all open exactly as one.

6. Use only one idle adjusting screw. Adjust to see start open + 1 turn.

7. Check that foot throttle linkage is free and connect to carb linkage.

8. When do above, adjust so no pull on carb linkage at all!

9. Start car and set idle.