TV cable adjustment is actually not too difficult, you just have to get the details right and be precise. Here is what I did. Geometry is critical.
I have a Holley carb. I picked up a throttle bracket that also has a TV cable bracket.
I picked up a TV cable from Rockauto for a 1988 Monte Carlo SS.
I picked up the TV cable adapter for my Holley carb.
Adjust the TV cable housing so it is all the way back towards the firewall. Connect cable to throttle bracket adapter. Slowly open throttle to full throttle. You will hear the TV cable click as it adjusts. Now let the throttle go back to idle.
At full throttle the cable should not be able to be pulled any further without it moving the cable housing. That is the full pull. At idle, there should be some tension on the cable - it should not be slack. With the cable disconnected and dangling, you will probably be pulling it from slack to around 3/8” to 1/2” to connect it to the bracket adapter at idle. This is expected and creates the initial tension and starting point of the TV cable.
Another thing to check - with the cable connected, measure the distance the cable moves from idle to full throttle as you move the throttle. It should move between 1.377” and 1.416”. This is key. If it does not move that far you have the wrong geometry on the throttle bracket and must fix it. Moving less or more is bad. Moving less is bad, but not as bad as moving more, because that will leave it slack at idle which means no pressure rise which can contribute to premature transmission failure.
Another way to think about it is this - once you have pulled the cable out as far as it will go, that is the full throttle point and it should always return back between 1.377” and 1.416” as you go back to idle.
You can additionally get a pressure gauge kit and ensure that at idle, as soon as you hit the throttle you see the pressures on the transmission start to rise. That tells you that you have the throttle start point setup correctly.
Again, none of this is difficult, it’s just precise.
(BTW - this easy to measure number for some reason is never really explained in many places. You see lots of the pictures showing the geometry, but this number is always left out. Basically, it is just some geometry math. The centerline of the throttle to the pivot point of the TV cable end is designed to be between 1.093” and 1.125”. It is supposed to travel in a 78* arc from idle to full throttle. This makes an isosceles triangle between the 3 points (throttle centerline, idle start, idle finish.) You also know the length of the two legs of the triangle and the angle between them. The third leg is the distance the cable moves. Doing the math tells you that the travel distance of the cable is between 1.377” and 1.416”, and that is very simple to measure.)
Could you elaborate a bit. I know they say you have to buy some conversion kit; but expensive could be $100 to $2000 depending upon who you talk to.