Need suggestion on new sbc engine

[Earthad58]

So I recently bought a 95 reinell 2030brxl with what I thought to be a 350 Chevy. The boat is 20' and has a wake tower. I noticed the engine seemed a little tired and after higher rpm runs when I would come to a idle it would smoke for awhile, blue ish oil smoke ( figured bad guide seals), well one day on the river I opened it up and held full throttle for prob 45 seconds or so and it was raving to roughly 5800 rpms and we got to about 45mph, then after that later that day I noticed it not wanting to idle well and had a tick coming from the engine, at this time I had good oil pressure. Long stores short took it out to the lake for the 4th and had a boat full of people and gear and towed a tube, well boat seemed wayyyy under power, wouldn't get up on plane without everyone moving to the front and even then was reluctant to do so, eventually the motor started rattling and seized. So engine was pulled out, torn down to find blownHead gaskets both sides. So far that's all I see, main bearings look good, rod bearing and Pistons look good, there was about 2 gallons of water in the engine so I believe it hydro locked and not seized, now, I ran casting numbers and turns out it's a 70-72 sbc 400. So I was planning on buying a 99 vortec 350 from a friend and I have a carved manifold for it. It had 150k on it from a wrecked suburban but ran great before pulled. I would like more power in this boat but don't want to spend a fortune, so, do you think I should retrofit this vortec in the boat or do a quick rebuild on the 400? I have a friend who owns a engine shop so I know I could get the 400 going for fairly cheap but the vortec is only $350, and it would need to run a electric fuel pump so there's another $70 ish, and I would probably have to buy a new flywheel as the vortecs have a different crank bolt pattern. Does anyone have experience with These motors? I know the 400 is supposed to be a torque motor which is good but the vortec is rated close to 300hp from factory.

 

[Earthad58]

Also I only paid $2500 for this boat so no I won't be buying a new engine, also this boat had the alpha one out drive

 

[Scott Danforth]

I would build the 400 myself with the vortec heads on it. what makes a vortec motor is the swirl inducing heads.

the differences in the flywheel are 1-piece vs 2-piece rear main seal, and internal vs external balance. you also have to match the harmonic damper.

however before you do anything. you need to find out where the water came from. once you do that, you need to pull the motor and see exactly what you have to start with. the 400 should have had a 2-piece rear main seal, perimeter bolt valve covers, siamesed bores at 4.125", and an external balanced crank with 3.75" stroke.

the '99 350 will have 4.0" bores and 3.48" stroke, and a 1-piece rear seal externally balanced crank

 

[Bondo]

well one day on the river I opened it up and held full throttle for prob 45 seconds or so and it was raving to roughly 5800 rpms and we got to about 45mph,

Ayuh,.... Welcome Aboard,..... 4800 rpms is redline for both of those motors,....

 

[Earthad58]

I found both head gaskets failed, water temp gauge wasn't working and overheated bad, warped heads. I inspected all bearing and Pistons etc, everything looks good, I'm thinking a cheap rebuild, rings bearings and either replace the heads or have them inspected and rebuilt. I also have access to a cheap rebuilt 350 that my buddy built for his boat and never used, .030 over flat top Pistons that's were good used, new rv cam and new bearings for about $300. Just don't want to spent a whole lot consider the boat itself was cheap and I planned on just not worrying much about it and just using it

 

[Earthad58]

Previous owner installed a pvc tee in the water pump coolant hose for a hot water shower and didn't get the clamps tight and found that the tee had basically blown out, so wasn't getting much coolant

 

[Scott Danforth]

I would mic the bores and the pistons, making sure you dont have an egged hole or collapsed piston. a new set of vortec heads is about $700 fully assembled. if you watch race junk you can pick up a set of low hour vortecs with new springs, etc. for about $400 a pair. a warped set of heads may cost you more than that to rebuild.

 

[Earthad58]

Yeah I hear ya, I may do that and drill the steam holes, I already got a Kodiak alluminum vortec intake, I'm dropping my engine off tomorrow and my engine builders machine shop and having him check it out.

 

[NHGuy]

The coupler and flywheel will add considerable cost to the 355. I'd redo the 400.
Make sure you have trustworthy exhaust. It has to seal the cooling jacket water out of the exhaust path. The spot where the exhaust manifold meets the riser needs to be nice and flat. Use the OE style gaskets there. The right gaskets are gray graphite impregnated metal mesh.
Also give the exhaust a good looking over It can't have clogged water passages or be rusted out. And it can't leak water into the exhaust tract anywhere.
A 400 is great as long as you keep it cool. Supposedly the siamesed arrangement can heat up, so don't keep it pinned on wide open unless you can monitor your temp and back off when needed.

Watch out for your wallet. I just built a 383 and spent way more than I started out planning. Good ideas just kept on coming...

 

[Earthad58]

Well went to the engine builder... He saw me coming... 400 is getting a full rebuild, .020" over, flat tops, marine cam, etc.... I guess at least when I'm done with the boat I can keep the motor for the next toy...