How i can adjust the kickdown linkage?

I'm guessing from your online name of "Aspen79" that you're working on a '79 Aspen. However, even if I'm guessing correctly, that's not quite enough information to give a complete response. When you ask "How do I...?" type questions, it's always best to provide as much information as possible about the car you're working on. Year, make, model, engine, transmission, carburetor type (1bbl, 2bbl?), emissions package if you know it (Federal, California, Canada?), and a description of any modifications you've made or repairs you've recently done that could be related to the problem at hand. It's better to give too much information than too little.

Generally, the kickdown linkage on a '79 is adjusted down at the transmission end of the kickdown rod. There is a clamp bolt-and-cube arrangement at the end of the trans kickdown lever. You loosen the bolt, which allows the rod to slide within the cube. Moving the cube rearwards lengthens the linkage -- upshifts occur later, downshifts earlier. Moving the cube frontwards shortens the linkage -- upshifts occur earlier, downshifts later. A little adjustment goes a long way.

If you're starting from scratch and need to get a baseline adjustment, first make sure the choke is fully open (disconnect the choke rod, open the throttle and push the choke all the way open to be sure) and the engine idle speed is set correctly. Then, under the car, while holding the kickdown rod itself as far forward /upward as it will go, move the cube forward as far as it will go and tighten the clamp bolt. This will give you a starting point to work with.

A good rule of thumb is that with the amount of acceleration needed to keep up with traffic when the light turns green on a 45mph road, the 1-2 shift should occur at between 13 and 17 mph, and the 2-3 shift at between 23 and 27 mph. Towards the lower speeds with a 3.23 or 2.93 rear axle ratio, and towards the higher speeds with a 2.76.

Thank you SlantSixDan