Any reason I can't put a 400 in where my 350 resides? I just bought a lot heavier boat and I can use the ponies.

Most people stroke out the 350's to 383 cubic inches. As I recall the 400's balanced externally, so it wouldn't be as simple as popping out the old motor and popping in the new motor. I'm sure it is doable, but would probably be cheaper to get a new rotating assembly for your 350 and increase the stroke that way.

Where are you in Moultonborough?

you will not be the first guy to do it.their is a guy in my neck of the woods with a pair of good running 400s in a 29 footer that has been rocking the river for 10 trouble free years.

This would be interesting

https://www.youtube.com/watch?v=HD77qNO6TP8

Not sure the Nelson Racing stuff would do so well with wet exhaust. And I am not a fan of dry pipes sounds, nevermind the cost of a trick motor. I'm aa working stiff, DIY.
I was on Moultonborough Neck. Our lake house was sold this year. Now I'm day dunking for this year til I get my Formula set up. Then I'll probably slip or rack at Fay's in Gilford. It's an easy drive from my house.

Not sure if you're talking about buying an old 400 sbc or building a new one.I don't remember any factory high performance models. They ran a shorter connecting rod, small cams and heads. You might consider the stroker kit mentioned above, you could go 396 or 408 with the 350 block assuming it's a good one. Best of luck

The 400 block was somewhat weakened in the main webs by opening the main journal diameter up unnecessarily. Then the cylinders have no water passage between the bores so steam holes are drilled through the deck and head as a compromise for coolant flow. You are much better off with a late model roller cam 350 block. Much easier to find, at least 20 years younger. And you are only giving up 23 inches from 383 to 406.

More cubes are always better.

What parts are you consideing for the 400 build ?

What exhaust and outdrive ?

BTW: What's the boat ?

You can easily build a 300 to 350 horse smallblock. If you stroke it out to a 383 you can build it to the hills, as long as your out drive will handle it.

Cool, that stuff about those old 400's I didn't know. My new to me boat has a 1997 roller vortec sbc. So either stroke that or buy and build one so I don't have to be boatless in the meantime.
The new boat is an 87 Formula 223LS with a 97 350 Mag carb & Alfalfa gen II. It has that Formula Silent Thunder muffler platform on the back. The heads were supposedly replaced last year when the PO f'd em up. It runs good, has decent feel, but I was kinda spoiled by the holeshot on my 2300 lb Baja. I never booted it but I didn't have to. That boat will accelerate nicely from any speed you choose, if you give the gas a little tweak it shoots ahead quick. I'll miss that part, but the Formula has a cuddy with a porta potti, and it crushes chop pretty well compared to my old boat. Plus it has some other nice features like power hatch, good lights and really nice front seats. I
I had it out for my first real boat day today and enjoyed it. Think it might be a keeper...til my pockets get deeper.