I have an image (one layer tiff) with 8 solid color.
Only one of these colors has a black layer (0,0,0,100).
I want to change this color (0,0,0,100) to (100,100,100,0) to clean the black layer of image.
when I use replace color tools, the texts are thinner.
How can I change color without changing the texts thickness?
You can copy>paste between color channels, so technically it's no more difficult than that. Note that 100-100-100-0 won't give you a neutral black! Inks have different densities.
Since these are CMYK numbers I assume this is going to an offset press? You need to watch the total ink limit. If you end up with 100-100-100-100 in some areas, you have a problem. The ink will smear and not dry properly.
Most CMYK profiles have an ink limit in the 280% - 320% range. This is built into the profile. A so-called rich black, printed on all four plates, maximizes ink on each plate to give the deepest black possible without exceeding the limit.
As only one image has black values, you could use Apply Image to “stamp” the K data to the CMY channels, then a curve to the K channel can easily remove all K data. Channel mixer may also be an option, however a CMYK test image would be needed.