Rob,...the vent holes are designed to help with the holeshot only. What happens is this:,....the exhaust gases will escape through those holes at the initial acceleration, which allows the prop to reach higher RPM's quicker, thus shooting you out of the hole faster,....after you are up and out of the hole and your boat is gaining speed, the exhaust gasses will go directly out of the hub as intended and no more exhaust will escape out of the vent holes. I know that Merc props are available with 3 different styles of plugs,.......solid, small hole and large hole.
These are removable and interchangeable so you can add or remove plugs to suit your performance requirements. Once I have my boat tweeked the way I want it, I won't mess with the plugs again, and to be honest with you, I'm not sure if the Merc plugs will fit your Raker prop, but you could certainly take your prop to a dealer and ask....wouldn't hurt to try!! Good luck.......and remember..."If it ain't broke....DON'T fixit!!" LOL
Good luck,
Mac
