Sounds like you may need to fnd a "bellcrank" that bolts to the back of the manifold. That converts the motion to what you want.

I have what I thought was the bellcrank but now with the new manifold I'm not sure. I think a piece is missing or it may even be the wrong one. The picture of the 55 bellcrank isnt anything close to what I have. It does fit the Y-block but ...

   We'd need to get Hoosier or Ted on this one, I only know that there's several different kinds of bell cranks, some for auto, some for Sticks. I didn't think that the 'Bird versions were different, but they could well be. John (Hoosier) has both pass cars and 'Birds, he'll know.

      Also, with the Blue Thunder and the late model carb everything is different anyhow. If it was me, I'd hit a junkyard and dig up the cables from a mid 60's Ford/Galaxie/ Fairlane/ Torino/Mustang and use those. I like cable throttles better than the rods, links and doo-hikies anyway.

I put a positive stop on the back of the intake manifold so that the pedal always goes right back to a common stop every time. The main "return spring" on the linkage takes back to that pointand it seats. Use a stack of washers so it can't move - I could never get a stable adjustment without doing this.

When the pedal height is good (4-1/4" lets you go clear to full throttle when it hits the floor) and you are on the positve stop - then you use that Phillips screwdriver seen in the second picture to get the "kickdown" lever into the proper spot. The diagram arrow to "original pedal height adjustment" is a threaded "Z" bar that lets this be adjusted to fit. You want the foot pedal at the right height for neutral idle - and the lever for the kickdown to be at the proper spots.

Then you set-up the rod to the carb (after setting up the idle). The angular travel of the four barrel primary throttle differs on the OEM teapot - the Holley 4160 - and the Demon 525 - so I don't know how to predict what hole is best. I took a measurement of the distance from the butterfly shaft to the operating rod hole on the teapot - and tried to match it.

When you reach this point you want to remove the set-up screw driver and try out the throttle return system. Rev the engine with the foot feed and let it off abruptly. Everything should return to stable idle. On the diagram, points C-A-B are almost in a row - when I didn't have the stop screw in the slot and you slipped your foot off the throttle - the damn thing would jump clear up to a "reverse toggle" with "A" much too high and jam. Only the positive stop helped get this to work right.

When the thottle will go to full and return to idle with no hitches - then set-up the kickdown. You pull up (not too hard) snug on the operating rod until it reaches the stop in the transmission - then adjust the half clevis to "just" fit on the stub you see just above the blue band of the screwdriver in picture two. Add one thread for freeplay.

The "kickdown" on the Ford-o-matic is basically just adjusting a pressure regulator valve inside the tranny. This pressure is supposed to be an internal transmission indicator of throttle pressure/position. When the over travel slot isn't blocked (as I told you I did) - the foot pedal takes the engine to full throttle - and then the overtravel continues to raise the kickdown pressure still higher - unitl it decides to "kickdown" to a lower gear. 

Actually, per the FOM manual I have, the kickdown clevis rod needs to be adjusted 3 turns longer than you describe.  Adjust the length to the point the clevis slips onto the pin, then adjust the clevis 3 turns to make the rod longer and lock it in there.  My FOM shifted really hard until i did this (w/ blue thunder & edelbrock carb, btw).  Also, the first time i did the trans, many years ago, I DIDNT do this, and had a premature failure - the bands for 3rd gear were cooked.... i had assumed this was the cause.

Keep in mind that this is listed as a preliminary adjustment, too.  The manual states that you should use a pressure gauge plumbed into the trans to perform finite adjustment - i havent done that yet.

For the record, I didnt have to convert any of my linkage when i switched intakes, etc.  Just lengthened the rods to adjust a slightly taller height...

hope this helps!

The Road Demon carb has an internal throttle return spring so stiff that the factory ford kickdown over-travel spring (and another larger one I tried) ...... allows instant overtravel - you push on the foot feed and all you do is move the kickdown lever. This is inverse to the way it should work. The Holley 4160 carb spring wasn't quite as bad - but neither of them were as slack as the teapot.

Yup, makes sense with really worn linkage.  I just posted the info to make people aware that its not always the case.  Id hate to see someone fry their trans as I did a long time ago.  Also, if anyone is experiencing hard part throttle upshifts, this adjustment will usually smooth them out. 

Obviously, every car/linkage is different, especially at this age!