water cylinder decarbonizing.. how much?

i have a 94 s-10 blazer 4.3L i have alot of carbon build up so im starting wiht steaming out the cylinders. In a previous post BlazerLT suggested that you use somethin like 1.75L of water, since i have a lot of build up i was wondering how much i should use?

Start with 2L and then take it for a drive and see if it helps.

Don't go overboard.