I'm trying to do an engine alignment, and when I turn the adjustment nut on the starboard mount the stud turns in the base. I sprayed it with PB blaster this morning, and I'm going to give it another shot later, but now I'm wondering if that mounting base is toast?

Been there , done that!! The new ones are not that expensive.
Call Mark Bentley at Bentley Power boats (920)743-7842, he is one of the best people I have ever dealt with when it comes to Merc parts!!

Did you catch my reply about the XE 274 cam? Are you going that way or what?

What you can do to free up the bottom nut is spray it like you did and get two standard nuts (thinner) and put both of them on the top of the threads and lock them togeather ( tighten them against each other) then put the wrench on the top nut and turn the stuck nut (very bottom ) one in a counter clockwiss turn. This should get it to move and maybe you can get to free up. Had to do this on BGIII ,s front engine mount. And NO it is not shot.

Thanks to "PB Blaster" I got it free and the engine is aligned!

TomZ,

I did get your reply, and I have decided to stay with the XM262. I ran a bunch of different cams through desktop dyno, and finally decided that the trade-offs in torque, idle quality, reliability, etc. just weren't worth the small horsepower gains.

I'm running stock vortec heads, and I think that they are the limiting factor at this point.

So for now it's going back together with the only mods being a new oil pan, dipstick, oil cooler and stat. Should be pretty bullet proof so maybe I'll get to enjoy boating for a couple years.

Very good.

After running it hard this weekend I might switch back to a less aggressive cam. I really pushed it pretty hard and got little out of what I thought I'd get... though a bit of it may be due to some bugs that need some getting rid of. It did run like a raped ape in the mid-range though... the boat was actually a little wilder than I thought it be.