260Z Carbs problem

R

Roels

Active Forum User
Hi,

A while ago i bought some 240Z carbs for my 260Z at Ztherapy.
Nice improvement in performance, but now i have a problem.
Sometimes the gas pedal 'sticks', as in when i get back to idle after driving, the idling runs a little too high ( 1500-2000RPM) but when i shortly pump the pedal, it gets back down to normal idle. I don't think that there's a problem with the alignment of the butterfly valves since the carbs are totally revised.. Could it be possible that it has to do with the linkage between the carbs? I also have the feeling sometimes that my gaspedal is quite hard to push when trying to be 'gentle'.
Anyone had any experience with this problem?
 
Oops, i meant Paltech1, not Ztherapy! Looked for carbs at both sites, but eventually got them from paltech1.
 
Well surely the first thing to do is to disconnect the linkage at the carbs and see if any part of the system is binding and that the carb operation is linear i.e. consistent resistance. The linkage rods can be adjusted to ensure they operate at the correct angles (arc).

Run the car without the pedal linkage and see if the throttles close correctly when 'blipping' by hand.

Do you still have a damper fitted and if so is that working smoothly and allowing full closure.
 
I had the exact same issue, you probabaly need to adjust the linkages slightly as Rob suggest's

Mine are now much better, but not perfect, i put that down to just being old and worn!

The accelerator/gas was a bit on/off, not very smooth at low speeds. There was noticeable slack
in the first linkage/pivot, the one connected directly to the pedal.
By removing, adjusting and refitting a few times, you can remove all slack, I set mine so there is barely a millimetere of free movement,
just enough so that nothing becomes too tight and binds up.

The engine will still occasionally hold the revs a bit higher than normal and need to be 'blipped'
but its far less frequent than before, and will hopefully improve with use :thumbs:
 
So you can adjust the linkage? The one between the carbs then? How do you do this? The top one coming from the pedal is pretty thight! Is it also possible that the springs attached to the linkage are not 'pulling' hard enough? I'll be looking in to it tomorrow.
 
Sorry to be that guy, but just replace the linkages with a cable set up...super smooth and fantastic pedal feedback. :thumbs:
 
Instead of using a s13 throttle wheel and cutting and welding it onto the SU linkage bar, I located a universal throttle that I have seen on most JDM cars equipped with triple carb conversions. Fitted that, made up a throttle cable holder (pivot point) and then just used a throttle cable from a Nissan Patrol. Universal cables from ebay etc would do job too. At the pedal end, (on my application) I already had a slot cut out so it was easy to hook up. I have seen small metal attachments that you can attach to pedal to convert to cable set up if needed. It's quite easy and logical mod ( I mean if I can do it...). Makes a massive difference esp if you have worn out linkages etc
 

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Blimey! I have exactly the same issue with my 260Z that has 240Z carbs fitted. They work beautifully in every respect EXCEPT that when the engine drops back to idle it ticks over at about 1200 revs. If I blip the throttle it then settles down to just under 1000 where it should be. Also when first applying the throttle on move-off it can come in a little suddenly.
I would be interested in knowing exactly how the linkages should be adjusted to correct this - because Datsfun's cable set-up solution is way beyond my level of understanding (even though it sounds great).
 
RIDDLER said:
Blimey! I have exactly the same issue with my 260Z that has 240Z carbs fitted. They work beautifully in every respect EXCEPT that when the engine drops back to idle it ticks over at about 1200 revs. If I blip the throttle it then settles down to just under 1000 where it should be. Also when first applying the throttle on move-off it can come in a little suddenly.
I would be interested in knowing exactly how the linkages should be adjusted to correct this - because Datsfun's cable set-up solution is way beyond my level of understanding (even though it sounds great).
Click to expand...

Just adjusting out any excessive slack will be a good start ;)

Also, dont forget to check the pedal is adjusted to correct spec and that the metal pin it pivots on is not FUBAR!
 
By adjustment I meant that the rods have threaded ends and can be adjusted for length. When doing that the arc they operate through can be changed. On my old car I discovered I wasn't getting full throttle but I was able to correct that.

Get someone to operate the pedal why you look in the engine bay.

Don't have such issues on my 370Z (fly by wire) just hope the two throttles don't 'play-up' when it's 40+ years old!
 
How about HAAAWYDKWTM?

How Annoying Are Acronyms When You Don't Know What They Mean
 
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