Engine Replacement

[Dustin]

Hey everybody new here, have curious on some opinions... I have an '03 maxum 19ft with a 5.0 305 i/o motor. Block is cracked so I will be pulling it out this summer. I am going to sell it as is (its repairable). I found a 5.7 350 i am going to put in. What kind of project am I looking at? I'm pretty knowledgeable of motors, is this project going to be harder than it looks?

[gonzo]

Are you replacing it with a marinized 5.7?

[Dustin]

Yeah I am replacing mercruiser for mercruiser. I have some friends who are trying to convince me into a 350mag from a chev truck but don't think thats a good idea. The drive is fine and will fit both motors with no conversion kit.

[marshmat]

Swapping Merc for Merc shouldn't pose too many issues. (Chev for Merc would be a LOT harder). Make sure the mounts are compatible before you start, and make new ones if they aren't.
The 5.7 adds a fair bit more power and weight, and that weight is concentrated in the stern. You might find the boat takes a bow-high attitude when on a slow plane, in which case adding trim tabs (or upgrading current ones) would be a good idea.
I hope the drive is a Bravo. The 5.0 is occasionally seen with an Alpha, a smaller drive which is readily torn to shreds by a 5.7.

[gonzo]

The 5.0 and 5.7 weigh the same. The difference is only on the bores. They both use 1.50:1 gear ratio. You may have to increase the pitch on the prop to keep it from over-revving. Everything fits the same: accesories, motor mounts, exhausts, etc.

[marshmat]

Oops- my bad again. Gonzo's right. Need to clean up the desk mixed up data for a 7.4 in there somehow. Now where's that hydro bill....lol