Replacing marine 5.7 vortec engine with a 5.7 vortec truck engine 1999MY

[evrk1]

Has anyone installed a 5.7vortec truck engine in a 1999 boat? I have heard that this can be done, but when I try to find out all the differences the issue becomes very cloudy. I just found a new 5.7 vortec truck engine on eBay and I would like to buy it and install it in my boat. I've heard that the cams are simular to marine cam, and that the only differences are the brass freeze plugs and cam. Has anyone done this and do you know what the differences are and what has to be changed. Would this be a good idea or just go with a marine engine. I'm new to this forum stuff, so excuse me if I make mistakes. Looking for advice or input. Thank you

 

[GettinBetter]

Re: Replacing marine 5.7 vortec engine with a 5.7 vortec truck engine 1999MY

I'd start with comparing the differences between the 5.7GL and your truck engine specs. I know the head gaskets would need to be marine spec, and anything that has raw sea water touching it would need to be changed. Alternator and starter are the other obvious things that come to mind.
I did a rebuild on a 5.7 recently and many the casting part numbers are dual useage and the 'truck' version came up time and time again, it seems (I believe) the 'GL and trucks have a lot in common.

Well thats my tuppence worth

 

[98LarsonGM57]

Re: Replacing marine 5.7 vortec engine with a 5.7 vortec truck engine 1999MY

Knowing that I am gonig to be unpopular for this statement.

Supposedly the valves and rods are not as stong - so if you are going to load this thing up and head to the grand banks daily you may have an issue; if you are just going to use it recreationally as I do - there is no problem

Supposedly the cam is not as hot and you will have less power - I got mine out of a 1996 tahoe with 199K miles on it; it was replacing a 5.7GS - the boat is actually a little faster than it used to be - absolutely everything was a direct bolt on - ZERO issues there.

Supposedly the freeze plugs are steel vs. bronze and will corrode - these are simple enough to switch out - I just added some pencil zinc in a few of the extra sender ports - cost $5; time 30 seconds

I've also heard the head gaskets should be switched as they may have a short lifespan - if you have the engine out - it's a 15 minute job; I did not bother - we will see what happens.

Good luck - took me 2 hours to pull the old engine; 2-3 hours to switch everything over and another 2 to put it in.

 

[98LarsonGM57]

Re: Replacing marine 5.7 vortec engine with a 5.7 vortec truck engine 1999MY

Also - you need a 96-99; the "95 vortec" has a different intake bolt set-up