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What's the difference between a 377 and a 383

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What's the difference between a 377 and a 383

Old 09-16-2019, 07:29 AM
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Default What's the difference between a 377 and a 383

I see they make a 6.3 liter 383 stroker and also a 377 stroker. Are both derived from a 350 block?
Old 09-16-2019, 07:45 AM
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Short answer is yes. The 377 which is listed as a 6.2L engine is a 350 block that has a .25 inch longer piston stroke which gives it the larger displacement. The 383 stroker is also a 350 block but it has been bored and larger pistons installed.
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Old 09-16-2019, 08:28 AM
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Originally Posted by gator1 View Post
Short answer is yes. The 377 which is listed as a 6.2L engine is a 350 block that has a .25 inch longer piston stroke which gives it the larger displacement. The 383 stroker is also a 350 block but it has been bored and larger pistons installed.
With the old small blocks:

The 383 is a .030 over 350 with a 400 crank (3.75" stroke).

A 377 can either be a 400 with the 350 stroke or a stock bore 350 with the 400 crank.

If it's an LS motor, it has nothing to do with the original small block except the bore spacing and the 6.2 is a stock displacement motor (along with the 5.3, 6.0. 6.6, and 7 liters)
Old 09-16-2019, 08:34 AM
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Originally Posted by gator1 View Post
Short answer is yes. The 377 which is listed as a 6.2L engine is a 350 block that has a .25 inch longer piston stroke which gives it the larger displacement. The 383 stroker is also a 350 block but it has been bored and larger pistons installed.
wrong. A 383 Stroker is a stock bore 350 block with a 400 crank. STROKE increased from 3.48 to 3.75.
Old 09-16-2019, 08:34 AM
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^^^^^idiots^^^^^

the answer is obviously six.
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Old 09-16-2019, 08:41 AM
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The current Mercury 377 is NOT a stroker, but rather a basic 6.2L 2v motor(mentioned by the poster directly above). The 383 is in fact a stroker 5.7 block and can be had in a 4V configuration for more power if wanted, but the 383 is mostly remanufactured engines from Mercury
Old 09-16-2019, 09:03 AM
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I just had a look. The 377 is 4.00 bore and a 3.75 stroke. The 383 is sold as a reman and is a 4.03 bore and a 3.75 stroke.

Since I doubt the extra 6 cubic inches is noticeable, from a Mercruiser perspective, the difference is new versus reman. And I think the way to go is reman since they’re emissions exempt.
Old 09-16-2019, 12:06 PM
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So the 383 is bored out .030 and stroked. The 377 is just stroked and not bored out.

Old 09-16-2019, 02:37 PM
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Originally Posted by fishmaster273 View Post
So the 383 is bored out .030 and stroked. The 377 is just stroked and not bored out.
yes.
Old 09-16-2019, 02:59 PM
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Originally Posted by porscheguy View Post

yes.
Are they both a 350 block?
Old 09-16-2019, 03:10 PM
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Originally Posted by fishmaster273 View Post
Are they both a 350 block?
yes.
Old 09-16-2019, 03:17 PM
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Originally Posted by porscheguy View Post
I just had a look. The 377 is 4.00 bore and a 3.75 stroke. The 383 is sold as a reman and is a 4.03 bore and a 3.75 stroke.

Since I doubt the extra 6 cubic inches is noticeable, from a Mercruiser perspective, the difference is new versus reman. And I think the way to go is reman since they’re emissions exempt.
Yep, no cat. Definitely the way to go.
Old 09-16-2019, 07:25 PM
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the 383 is called a reman but in reality all the parts are brand new
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Old 09-16-2019, 07:41 PM
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You lost me at 373 vs 383.

This is why I appreciate the members who provide valuable input on this forum. This is way outside my area of expertise. This site is always a backstop to provide a sanity check. I've owned a couple of boats, but never had any time, or interest in getting into specifics into engines. Thanks guys. I'm a weekend boater, who keeps up with maintenance, and expects the damn thing to work when I turn it on or press the start button.

Appreciate you all taking the time to offer your assistance.

I'll start a follow up thread on seagulls and the ungodly amount of excrement they produce....

Salty
Old 09-16-2019, 08:02 PM
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Originally Posted by porscheguy View Post
I just had a look. The 377 is 4.00 bore and a 3.75 stroke. The 383 is sold as a reman and is a 4.03 bore and a 3.75 stroke.

Since I doubt the extra 6 cubic inches is noticeable, from a Mercruiser perspective, the difference is new versus reman. And I think the way to go is reman since they’re emissions exempt.
That makes sense , clean up the old cylinders bore 30 thou - less then 1 mm . That's only 15 thou off the cyl wall your just making it nice again .

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