I have heard many comments (mostly good)about port plates. Have there been any independent tests done on an engine with and without them? Anybody have any comments on them?
Original Post
I assume you're talking about the intake side. Plates are made for both intake & exhaust, but may be more effective on the intake side. Exhaust plates affect the intake draw as well as back-pressure, so the carb needs re-jetting with either type to be 'correct'. Someone in the Nor-Cal POCA chapter found this out recently: he mounted a set on 4V heads with a 4V Edelbrock Torquer intake. Whatever cam & carb the engine had, it ran badly on the dyno, ran rich and made little power. Possibly better than intake- side port plates is simply using a swap-meet 2V intake. The 'step' at the 4V head/2V intake junction acts as an anti-reversion point just as the plates are supposed to. The low end on one seriously built-up engine increased tremendously, but the engine ran out of air around 5500 rpms. The owner thought it was much better for the street where you don't use hi revs much.