I'm trying to imitate a certain style of mouth animation that can be seen in most animated TV series up to the 1990s.
First, let me explain what I'm talking about. This particular technique uses only 6 fixed mouth shapes, named A-F. Sometimes a 7th or 8th mouth shape (G/H) is used. A is a closed mouth, B shows clenched teeth... For a ful list, see this link. There are no additional inbetween drawings, but, for instance, the C shape can be used as an inbetween between A and D.
Examples for this style of mouth animation include Scooby Doo, The Smurfs, Dexter's Lab, and Darkwing Duck. It seems to have been a de-facto industry standard, but there is very little information available on how best to animate in that style.
I read the chapters on lip sync of more than a dozen books on animation, but none of them covers this specific animation technique. I'm looking for any books, websites, or other resources that cover that particular style!
Sounds like the lip sync style you are talking about is the one where the make a library of talking heads. It was not lip sync, it was just a simple samll series of basic mouth shapes. The dialog would never sync up with the lips of the character but it was close enought. Have to cut cost where ever possible.
Yes, we're definitely talking about limited animation, i.e. saving cost by not drawing each frame from scratch. Though I don't agree that "the dialog would never sync up with the lips." In many cases, the results were excellent.