SU help

[mars23z]

I am having a problem with my 260z I have Switched to the su side drafts The car starts fine idles fine evrything seems ok but when it warms up if i accelerate above 3000 rpm the throttle sticks and holds at about 3-3500rpm Now from what I under stand the carbs have something that is suppose to hold the throttle briefly and then come down to prevent stalling but I have to force mine to come back down by braking without pressing the clutch witch is a real pain to stop. If I push the clutch in it just sicks and revs at like 3-3500 rpm. What do I do?:sick:


Thanks Mars

[wfl_colorado]

Might be the throttle linkage and/or the carbs. Operate the throttle in the engine bay and see if it is sticking. If not, look to see that the basic carb function is working properly.

Bill

[=Enigma=]

I can't remember the name of the item you are referring to but somebody will. I believe it is vacuum operated and connected to the throttle linkage. To test, try disconnecting the linkage or the vacuum hose from the throttle linkage. Anyway, here's a bump for ya.

[Walter Moore]

It is called a throttle opener or something like that. It is a vacuum operated device that mounts on the intake balance tube and holds the throttle open supposedly for a short time when you shift gears. It looked bad on my engine so when I rebuilt everything I removed it and plugged the holes in the manifold.

But since I haven't started my engine YET.... I have no idea if removing it is a good idea or a bad one.

I think it was supposed to be an emission control device, or an anti-backfire thing or something. It has a linkage that connects to the throttles. You might try to just remove the interconnect linkage and see what happens.

Assuming of course that Enigma and I are even on the right path. I can't speak for him, but I am mostly repeating things I have read in a manual somewhere.

[beandip]

Check the linkage that connects the two carbs together . If you grasp the rod and cannot find any play from side to side , that is the problem. Are you using this part of the linkage from the old Flat tops ? At least this is a good place to start looking for sticking throttle linkage. The center linkage should have a loose fit if it is the correct one. That's my thoughts . Gary

[beandip]

I can't remember the name of the item you are referring to but somebody will. I believe it is vacuum operated and connected to the throttle linkage. To test, try disconnecting the linkage or the vacuum hose from the throttle linkage. Anyway, here's a bump for ya.
I THINK YOU ARE THINKING OF , DASHPOT . LOL

[beandip]

This thing and I think it is called a dashpot , has been removed from my engine for over 5 yrs .

[Bruce Palmer]

Have to ask the obvious. What are the return springs on the carbs hooked to?

[Darrel]

n/m, ,,,,,,,,

[mars23z]

thanks for responding I am thinking of removeing the devise altogether i hope this will fix it I think everything else works so it has to be the vacuum devise that was what I was talking about in my original post or trying to talk about

[astrohog]

was having the same problem on my '71. I finally found the culprit. It was the "slow idle return" thing. All I had to do was back the screw out 2 turns and the problem went away. I have noticed, however, that when I shift gears, the idle does want to return to a low idle rather quickly and can make for some rough shifting. I will give it awhile to see if I can get used to it, or I will try to find a new unit and/or fine tune adjust the one I have.

Astrohog

[Pir0San]

you guys are thinking of the Boost Controlled Decelleration Device, or BCDD. It is only present on the fuel injected cars, and is used to slow down the drop in engine revs when driving to fully burn fuel when the engine is raced and then the driver decides to slow down.

[mars23z]

The part I finally removed I think was the dashpod what ever it was it fixed the problem thanks

[astrohog]

Actually it is called the "throttle closer delay diaphragm" and it did come on the carburated engines. I took mine off and fixed my problem. When I went to the Nissan dealer, he said they are not available anymore.

Regards,

Astrohog