It does not in anyway specify 24, much less 24 hours.
By the way, since you are relying upon the infallibility of human language, perhaps you'd like to compare the use of any number of words which have changed conotation in the last 50 years just in the U.S., much less the changes between the time the King James Bible was translated, and now.
There are several other layers of things you are overlooking in making such a brash claim.
And just because you will probably come to this sooner or later: I believe that God created the Heavens and Earth. I just think you undermine your own case with your claims.
First, my claim is on fact, nothing "brash"
Second, I've undermined nothing by stating the Biblical case. THere is no need to compromise truth for the best guesses of scientists when truth fits.
The word used for day is (Strongs 03117) yowm (pronounced: yome). This word when used with a number (first, second, etc) ALWAYS in HEBREW means a literal 24 hour period. That's the way the Hebrew has always been.
So yes, Scripture DOES clearly specify a 24 hour period. And to make it even MORE clear, God uses "the evening and the morning" before it -- just to make sure people wouldn't play fast and loose with the term.
Sadly, they still do.