I have been told some marine engine turn backwards in rotation than a normal car engine. maybe someone will chime with more marine experience.

 

Bottom ends are slightly different . I know they come stock studded. In 94 and 95 the 4.3L had a HD block which ran a really have casting compared to earlier marine and car blocks.

 

no marine motors are not counter roating. that was a very slim production hickup. you should be able to swap no problem. it might not have the mech fuel pump so elect will be needed. other than that should work. cam isnt going to make that big of a diff if you dont wanna swap them

 

Twin I/O setups have the second motor spinning reverse rotation, to reduce cavation of the impellors. So any boat that came with twin 4.3's (if there were any) would have had one rotating in each direction.

To the OP, you need to change the head gasket to use a truck motor in a boat, unless you're only going to use it in fresh water

 

There were a lot of boats that used two GM 4.3L motors but were labled as Volvo.

 

THANKS FOR ALL THE HELP!!! I figured that there would not be a problum swaping them out. It is a fresh water boat and I now have another project to finish befor this summer

THANKS AGAIN

 

How did you make out I did the same but have turned a bearing twice now

 

So I have a Chevy 4.3 vortec if I change gaskets freeze plugs an such you saying it will work that yours did work

 

Most of these guys haven't been on in years.

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