Lonnie, do you mean exh crossover like Mark said or EGR ports?
I take it you are talking the cast-in air injection nozzles in ford exh ports? Since you can't grind them or anything I wouldn't think blocking them would help but I could be wrong. Normally I just put a plug in the back of the head where the transfer tube connects, leaving the internal cast-in passages alone. Here's a picture of a chrome tube still connected;
http://www.supermotors.net/getfile/3...e/xtubenew.jpg
Are you thinking of putting eight tiny plugs in the "nozzles" that protrude into the exh port?