mercruiser 5.7 block replacement

[hermannm]

Quick question. Can i replace the block of a 5.7 mercruiser with one from a chevy truck? I know the freeze plugs need to be chaged to brass, then i would take all the old accessories, pistons, etc from the old motor and put in the auto block. Any concerns or comments from doing this? I know mercury used the GM engine, I can't imagine they forged a special "marine" block

Thanks

 

[Bondo]

Re: mercruiser 5.7 block replacement

Ayuh,... Same Blocks, No Problem,... Be careful of the Vintage thing....

 

[hermannm]

Re: mercruiser 5.7 block replacement

Vintage thing?

 

[fyrfightr]

Re: mercruiser 5.7 block replacement

Older 350s had a 2 piece main, newer have 1 piece.

 

[mnypitboat]

Re: mercruiser 5.7 block replacement

Should be the same. I have an 01 Vortec 350 currently in my boat. The one I am putting in my boat ia an 88 non vortec, but the blocks are practically identical other than the vortec heads and the components. My buddy has a 87 Camaro block that appears identical. So they should be the same.

 

[171mach1]

Re: mercruiser 5.7 block replacement

I think a Vortec uses a roller cam, I don't think a Vortec and a non Vortec block are interchangeable. but then again I'm and old Ford guy.lol

 

[mnypitboat]

Re: mercruiser 5.7 block replacement

Right, forgot about that, you are absolutely right, they are not interchangeable. So you have to determine whether you got the right one. They do look identical though.

 

[BrandonS]

Re: mercruiser 5.7 block replacement

Vortec engines are interchangeable with non-vortec engines. The difference is in the heads and intake manifold. Vortec heads have a different intake flange angle, and thus, must use a Vortec intake. The block and lower rotating assembly really hasn't changed in years. the only things that change in the lower assembly are the piston tops, crank stroke, and rod length. But, for the most part you will never have to worry about that, none of the changes are significant enough to effect clearance.

Brandon

 

[171mach1]

Re: mercruiser 5.7 block replacement

so your telling me a non vortec block has the provisions to accept the lifter guild plates used with the vortec's roller cam?

 

[Bondo]

Re: mercruiser 5.7 block replacement

the only things that change in the lower assembly are the piston tops, crank stroke, and rod length.

Huh,..??

Seeing We're talkin' SBC 350s,...
Crank stroke hasn't changed.... It's 3.48"...
Nor has Rod Length... They're 5.7"...
There's has been a couple different pison tops used,...
Provisions for the roller cams came about when the 2 piece rear main seals went to 1 piece in 87...
And,...
As noted, the Vortec is All about the heads,+ the intake manifold change, Nothing more...
Oh,... In 79, the dipstick moved from the starboard side to the portside....

 

[180shabah]

Re: mercruiser 5.7 block replacement

so your telling me a non vortec block has the provisions to accept the lifter guild plates used with the vortec's roller cam?

YUP!

Vortec is a head introduced in '96 and a marketing name started in the 80's

GM, been using the roller cam since the switch to 1pc seal in '87.

 

[171mach1]

Re: mercruiser 5.7 block replacement

YUP!

Vortec is a head introduced in '96 and a marketing name started in the 80's

GM, been using the roller cam since the switch to 1pc seal in '87.

That's good to know!

 

[Cptkid570]

Re: mercruiser 5.7 block replacement

The cam is different in an auto application than a marine. If you do go with an automotive engine, go with a truck because the cam is more similar to the marine cam.

That said, where are you going to get your engine from? When I bought my marine longblock, it wasn't much more than an auto long block (if any more at all).. got mine from Rapido.

 

[Silvertip]

Re: mercruiser 5.7 block replacement

And also forget about using the pistons from the old engine in the replacement block. Bad move as they are not "fit" for direct replacement. Chances of that action lasting are slim to none. If you found a truck engine, simply re-ring it, check the crank while it's opened up and install new bearings. Unless the existing engine has a cracked block or some other damage that prevents it's rebuild, there is no logical reason to buy a used truck motor, then remove internals from the existing engine to install in the replacement. That simply is not recommended.