Kickdown linkage WOES!

[banana70]

Hello my dear fellas... I'll try to make it short..

I installed the original linkage that came with my 2bbl 318 (1974), but now the intake manifold is the MP-M1 single plane and the carb is a demon 750.  We installed everything to specs but the bracket with the channel that goes in the stud where the accelerator cable goes was too far back and we fabricated an extension to make it fit.

The symptoms vary depending on two settings: 

1) With the bracket installed in a way that it only actuates over the linkage when half way (secondary starting to open) is reached, the shift from 1st to 2nd seems normal and 2nd to 3rd is weird.. rev seems to go up for a moment and then 3rd gear comes to place..
If I step into it, shifting becomes a little better but the upshift is also weird...

2) With the bracket installed in a way where it actuates on the linkage as soon as the throttle starts to open the shifts are perfect, but when the linkage reaches the maximum action the throttle is only half way and it cannot go further (secondaries are not able to open).

Questions

a) Is the setup correct where the carb stud actuates on the linkage as soon as it starts accelerating?

b) Somebody told me that the problem I have now is the geometry and that i need to find a way in which the whole travel of the carb throttle is accompanied by the kickdown linkage all the way, is this correct?, how can I do that?

c) Is the lokar cable (or similar) the solution to my trouble or maybe in part?

d) is it true that if you simply eliminate the whole kickdown system (and shift manually) you will kill the tranny?

Thanks in advance....
PC

[Chryco Psycho]

the Lokar may be the best solution , I have always adjusted them so you get the kickdown as far back as possible at WOT

[tactransman]

b) Somebody told me that the problem I have now is the geometry and that i need to find a way in which the whole travel of the carb throttle is accompanied by the kickdown linkage all the way, is this correct?, how can I do that? The easiest way to do it is to copy what the system was like before the mods,the distance from the throttle shaft pivot point to where the carb  rod pin is,(the swing "ratio")and where the carb rod pin is starting out it's "swing" to in front,above or behind the carb throttle shaft.I hope i made that clear,it is hard to explain.
c) Is the lokar cable (or similar) the solution to my trouble or maybe in part?It can be your "plan B"

d) is it true that if you simply eliminate the whole kickdown system (and shift manually) you will kill the tranny? Yes,that is true.

[ShelbyDogg]

Did you add the bracket that Mopars use to the carb arm?  Also when you change to a taller manifold, you have to check for the stuck-at-wide-open-throttle problem, caused by the kickdown going over-center and holding it there.

Rob

[brads70]

Did you add the bracket that Mopars use to the carb arm?  Also when you change to a taller manifold, you have to check for the stuck-at-wide-open-throttle problem, caused by the kickdown going over-center and holding it there.

Rob

Rob, I know this is an old thread but do you have a picture of this bracket on the carb that you mentioned? Were you talking about a Holley carb? Mine does seem to go over center? Engine is not running yet just want to avoid any potential problems.
Thanks Brad

[ShelbyDogg]

Here brad,

http://www.cuda-challenger.com/cc/index.php?topic=57503.0

I have all 4 speeds now but I think an easy way to fix this would be to make that little hinge link a little longer.  Does yours stick down like in my drawing? If so, you can see why that short link binds up by not being able to push farther towards the rear.  Glad you found it before you crashed it.

[brads70]

I don't have the same linkage as you I think. I'm using the Lokar set up. It clips on the bottom the the carb linkage ( Holley) It's just when I move the throttle through it's travel it looks like the kickdown goes over center. If the carb linkage was longer ( went back towards the firewall) that would solve it?

[ShelbyDogg]

I have never used anything but stock or modified stock linkages so I can't picture your setup. Every holley carb should have the Mopar linkage put on it if it didn't come with it. It is an extra bracket that bolts to the side of the throttle arm that extends it about an inch away from the carb and a little higher up.

[Bullitt-]

Read in the service manual something I've never heard mentioned..Has to do with keeping the kickdown shaft at the tranny positioned fully forward while you adjust at the carb.. They show a "tool" a flat bar with a D-hole to slip over the shaft & a spring to pull it forward, you connect it to the front of the tranny.    Then you adjust at the carb so that the throttle lever contacts the slotted bar at the rear.