Hey, I'm looking to find what the RPM should be when the engine is wide open on an '84 OMC I/O 2.5L engine (model 252STHRCRA.) We bought the boat used and it didn't come with the owners manual. Right now we're specifically wondering about the RPM to replace a prop, (we don't know if the prop on it is the ideal, but we heard you can find out the ideal by using some equation with the boat's current RPM and the ideal RPM when it's wide open.) If anyone is an expert on this engine and has any other helpful advice, we'd love to hear anything you have to give us! This is our first boat, so we are soaking up all the info we can. Thanks!