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vanstee
06-22-2005, 10:49 PM
Still messing with my prop problem. as a recap, I've got an 88 ragazza, 3.0L. Has the V6 outdrive lower unit. original prop was 13-15. when the outdrive was replaced, tried a 15-15. couldn't get the boat on plane and engine lugged. So, switched to a 13 3/4-15 and at about 2800 RPM's I cavitate it. Any suggestions? i'm ready to shoot it and sink it and put it, and me, out of our misery.
Thanks!

MOP
06-23-2005, 05:25 AM
Still messing with my prop problem. as a recap, I've got an 88 ragazza, 3.0L. Has the V6 outdrive lower unit. original prop was 13-15. when the outdrive was replaced, tried a 15-15. couldn't get the boat on plane and engine lugged. So, switched to a 13 3/4-15 and at about 2800 RPM's I cavitate it. Any suggestions? i'm ready to shoot it and sink it and put it, and me, out of our misery.
Thanks!

I remember you had the drive done over, it was sugested back then that you check the drive ratio. Did you do that? If not you can get a pretty good idea by marking you engines front pulley I use white paint on the -0- line, then mark the prop. Remove the coil wire, have some friends help to watch the pulley and one to watch the prop while you slowly tap the motor over with the starter. !988 has 1.71 later 1.86 to 1 so you engine should turn roughly 1-3/4 turns to 1 revolution of prop. I still think tha shop screwed the ratio up!

Phil

vanstee
06-23-2005, 08:12 AM
I remember you had the drive done over, it was sugested back then that you check the drive ratio. Did you do that? If not you can get a pretty good idea by marking you engines front pulley I use white paint on the -0- line, then mark the prop. Remove the coil wire, have some friends help to watch the pulley and one to watch the prop while you slowly tap the motor over with the starter. !988 has 1.71 later 1.86 to 1 so you engine should turn roughly 1-3/4 turns to 1 revolution of prop. I still think tha shop screwed the ratio up!

Phil

Yes, checked the drive ratio and it seems ok. Ill check it again to be sure though. I looked in another service manual (the one at the shop where it was redone) and thru 89 it shows the same lower unit ratio for the 4 cyl and 6 cyl lower units which counterdict's the one you emailed me. Looked at a third one and it shows something completely different, a 1.91 if I remember correctly.

I'm suprised that 1.25 inch diameter can make the difference between caviataing and biting too much and lugging. Maybe the 15 wasn't a 15 after all?