Here are a set of rules from the man who is arguably the “Father” of American Wargaming, Jack Scruby: Basic Wargaming Rules.
Rules: 18th Century
54mm French and Indian War Rules
The MAWs offer a set of free wargames rules for the French and Indian War using 54mm figures.
The Immortal Memory
The Immortal Memory is a set of rule for refighting Trafalgar.
Wargames Rules 1685-1845
Wargames Rules 1685-1845 is a set of classic WRG rules from 1977. I own a copy, but you can get your own in pdf form at the link.
Two Page Tricorn
Two Page Tricorn is a set of rules for 18th century warfare. It is designed for the quick resolution of large scale battles, ideally using 6mm figures.