So... took the Miller out Sunday. Engine runs GREAT!!
Last year, the boat pulled hard, topped at 70MPH at 5200 RPM.
Now, at around 60 MPH , it starts to "rattle" and vibrate, and the engine "revs". I am certain that it is cavitation.
As soon as you let off, it stops and will cruise like a swiss watch right up to 60 or so. There is PLENTY of motor left, just wants to suck air.
When I had the intake reset this winter, I did notice that the "spoon" or lump before the grate on the bottom had been removed.
Is this generally enough to cause cavitation at speed?
The pump mods were a droop and Hyd. place, new detailed A/B. No shoe or plate.
It doesn't matter where I trim it, at 60 MPH it breaks loose.
The boat wants to go, and I am certain it will pull hard far past 70 MPH comparing it to how it ran last year.
So.. Is the removal of the "lump" on the bottom capable of causing this? If so, how should I build it back?
I have had this boat for 3 years, 3 different engines and have NEVER had it cavitate before now.