does anyone use them and how do they work?

 

Usually port plates are used in 351 Cleveland 4V Heads and Boss 302 Heads The reason a port plates are used is to take up space inside the port . The ports are so large for the 302/351 size engines that they were on that there is no velocity (air speed) in the port. So port plates are thin sheet metal that protudes down inside the port. It close up a area in the port usually the floor area, which decreases the port volume and increases the velocity(air speed). But I'm not aware of any port plates made for 460's or that there would even be a need on them, a company in Indiana Price Motorsports used to sell a pair of Aluminum High Port Exhaust Plates for a racing 429/460 where you put the head on a mill and cut the exhaust side of the head clear off, you then bolted these plates on to what was left and it raised the whole exhaust port upward. Now this was exteme stuff for hard core racing. But unnessary now days with all the good heads available. Hope that give you some idea of what they do. A company called MPG used to sell the plates, you might dig around on the web If you want to learn more. Good Luck Tom