Building a 383 stroker boat engine

[The motor guy]

I'm thinking of building a marine 383 stroker since it looks like you can get a bare gm350 block for about $1100.00 then take it to a machine shop and have it made into a 383 and install all the guts.

Now is this a good way of doing it or should I just buy a long block and be done with it?

My thinking is I can build it with the proper piston and have it internally balanced to last longer. Or will the standard factory neutral balance suffice? I think the engines are neutral balanced, maybe not.

I can't seem to find any new 383 blocks, but I can find a 377 which is 6.2 liters and I believe it is a new block, not remanned.

 

[SteveSRT8]

I vote for a pro built engine. Find that killer shop with the street rep and they will take care of you. BTW, a 383 is just a 400 crank in a 350 block. Just needs a few tweaks and makes a very torquey engine.

Since we have a 3rd gen machinist in our family we no longer try to cobble one up by ourselves. Our man just took in a 20k crate motor for 10-15k worth of fancy work. he built my son's 6.0 into a monster, too.

 

[thastinger]

For something that sees more than a few hours of run time a year, IMHO the increased rod angle of the stroker 383 isn't worth the wear rate over a 350.

I assume you're going to run dry manifolds and risers? If not, your cam choices will be limited...another reason to not do a stroker.

 

[ARCOgraphite]

Just a 350 should suffice. Vortec head Crate motor for 2 grand and epoxy coat where needed for marine use. Then install a circle track cam with the torque peak where needed. You'll be making so much more power than stock you wont know what to do.

You don't want to kill the outdrive.

What is your max prop speed and drive reduction 1:83??

 

[The motor guy]

1.95

 

[ARCOgraphite]

You have a sixer back there now?


Where is our resident Marine Mechanic expert. Haven't hear from him in ages!

 

[The motor guy]

Yes the manifolds will be wet. My concern is the shop won't build it with the correct cam duration and it will ingest water.

 

[The motor guy]

https://www.michiganmotorz.com/377ci-stroker-base-marine-engine-2000-2019-replacement-p-545.html

I'm thinking something like this. Then I'll add all new accessories and fresh water cooling.

 

[bullwinkle]

Correct me if I'm wrong, but I believe 400 cranks are nodular iron? Not sure if forged ones were ever made?

 

[CT8]

What kind of boat is this. I missed something? I have built several boat engines over the years which were big block Chevrolets.. There is no magic or voodoo required. If the engine builder is superb the engine will be fine and the proper cam etc will be used and the engine builder will to what is proper because his name is on the engine. Would you use anything but a superb engine builder? Usually a crate motor is the best buy if you don't know a superb engine builder . Circle track cams duration aren't the best for wet exhaust

 

[The motor guy]

It's called an abermarle 24 loaded down with fuel the boat weighs about 6000 pounds plus passengers.

 

[The motor guy]

My concern with doing the long block is although it saves money, I'm worried about problems adding on all the accessories and it taking way longer than anticipated.

Is their a set place for you to mount stuff to the engine? Like what if I want the power steering to go down lower and the cooling tank up front? Can that be done?

 

[The motor guy]

Am I not going to get 2500hrs out of a 383 like I did the 350?

 

[OVERKILL]

This the boat?

Personally, given how much better the LSx engines are over the venerable SBC, I'd be inclined to pick up a marinized 6.0L or something similar and toss that in there.

This article explores the differences and what's required to mate an LSx up to something that previously had an SBC mounted to it, sounds like there is not much to it:
https://www.hotrod.com/articles/legacy-manual-trans-behind-ls-style-block/

 

[The motor guy]

Yes sir that would be it.

 

[The motor guy]

I'd like to stay with the same block to keep the same size and weight. It's a bit of a tight fit in the engine box.

 

[OVERKILL]

Originally Posted by motor_oil_madman
I'd like to stay with the same block to keep the same size and weight. It's a bit of a tight fit in the engine box.


Isn't the LSx more compact? I was under the impression it was

 

[redhat]

Oh yes, LS is way more compact.

An eBay set of 1" set back plates, stock SBC clam-shell mounts and an LS goes anywhere a SBC did.

 

[thastinger]

With wet risers I don't see the upside to the stroker option as the cam can't be optimized, too much lobe separation and you'll hydro the motor.

You'll obviously need to stick with cast iron heads and manifold. Most 383 crank/rod/piston sets are geared toward racing so they have higher static compression. You probably wouldn't want that unless your marina has 93 octane non-ethanol fuel.

 

[OVERKILL]

Originally Posted by redhat
Oh yes, LS is way more compact.

An eBay set of 1" set back plates, stock SBC clam-shell mounts and an LS goes anywhere a SBC did.

that's what I thought. The LS would be a wicked upgrade, and I expect there are a number of them sold as injected drop-ins.