Throttle Stiction

[Albert]

My 1971 240Z has throttle stiction which makes it very jerky when starting off from a standstill. I have had all the linkage apart and lubricated all the ball joints and linkage parts. I have replaced some still ball joints with looser joints and I have had the throttle pedal assembly apart and lubricated that.

Has anyone any ideas what else to try ?

I have read on the US forums that this is a known problem and some people recommend refabricating the bell crank to have a different angle on it. Seems drastic although the throttle seems very sensitive to small movements of the pedal which could point to that.

Thanks

 

[datsfun]

Have you considered binning the factory set up and replacing it with a cable instead? Easy and cheap fix which takes away all such "sticking" issues..

However if you want it to remain " as it left factory", then cable set up isn't an option.

 

[Albert]

yes I would consider it if I cant resolve the problem. Is it a common problem do you know ?

 

[Rob Gaskin]

yes I would consider it if I cant resolve the problem. Is it a common problem do you know ?

From my experience of three 240Zs no.

Try adjusting the lengths of the threaded rods to alter the angles.

I remember having to do this to get full throttle on my track car.

 

[MaximG]

Go through all the joints first to make sure they are free. Also look to see if the carpet is causing an issue. Grease up all the moving parts as well. Personally I have never had a problem with the original setup.

 

[Albert]

Thanks Guys,
I think it must be down to the angle of the bell crank and the other joints as its all lubricated and there is no carpet in the way etc.
Rob do you recall what is the optimum angle of the bell crank ? Would it be straight 90 degrees to the rods ?

 

[Jimbo]

mine used to get stuck at idle (have mechanical resistance) so you would have to press a bit harder when pulling off which caused a jerky takeoff and it was the throttle butterfly's binding at idle in the carburetor due to my worn throttle spindles on 240 carbs.
i change the carbs over to SU hs6 carbs to fix other issues and the problem with sticky throttle completely disappeared.
maybe try spray some wd40 into the bearing are of the throttle bearing and see if it gets any better.

 

[Albert]

Thanks Jimbo,
Would I have to disassemble the carb body to get at the bearings ?

 

[SacCyclone]

I would disconnect each of the joints one at a time to try and locate the sticky part.

I don't believe the throttle shafts have bearings, and they are known to wear and suck air. Have not heard of them sticking but maybe binding if something has bent.

Good luck.

 

[Jimbo]

I would disconnect each of the joints one at a time to try and locate the sticky part.

I don't believe the throttle shafts have bearings, and they are known to wear and suck air.

Good luck.

apologies not bearings i should have said bushings

mine were worn so were leaking in air and with a bit of side to side movement caused them to jam at idle position against the body of the carb.

albert- like saccyclone says disconnect the linkage between the carbs and throttle rods and turn the throttle of each carb and see if one of them is binding up it should seem quite obvious