Prop suggestion 5.7 litre OMC

[FinLander]

I have a 1986 Sportsraft Sportsman 250 that I bought last Fall. Over the winter I changed the motor from a 5.0 litre chevy, to a 5.7 litre. Motor is a fresh Marine long block. The outdrive is a OMC Cobra. The previous owner of the Boat had painted the lower unit and Prop with anti-fouling paint, and I have been unable to find any size on the current prop. My current problem is that the boat is slow to get on plane, and can only achieve 4000 rpm at WOT. I have gone through the ignition and fuel systems completely and the motor does run good, it just doesn't come out of the hole very well and seems to be low on RPM at WOT. I am looking for the manufacturers recommended WOT rpm, and OEM prop for this configuration as a starting point.

 

[steelespike]

Re: Prop suggestion 5.7 litre OMC

Unless you can find that particular application (not likely) we need the prop size.With max recommended rpm, prop size,present rpm and gps speed prop suggestions become a lot easier.If you can't find numbers a prop shop can measure it for you.

 

[FinLander]

Re: Prop suggestion 5.7 litre OMC

I was finally able to find the prop size on my prop it is 16 x 16p. According to the dealer I spoke with, he told me I should be getting 4400-4600rpm @WOT.
Currently I'm getting 3800rpm @WOT, and my GPS speed is 29mph. Any suggestions would be appreciated