i think what Allan means is......if you have 3 ports to your petcock,you probably have a vacumn port on your carb to make it work.
if so,you will need to block the hole to the carb,a tube and a golf tee work well.
i think what Allan means is......if you have 3 ports to your petcock,you probably have a vacumn port on your carb to make it work.Its an '80