Ok, here is what I've found.. It's a Marine Engine, Mercury 5.7L EFI.. The block is cracked, so thats no good.I do know that they are all GM blocks.. . But what about the heads? would they be ok.. and what about Marine Cams.. Thoughts on those.. it's a new engine (well at least it was). I'd image everything is in good shape.. IE springs, lifters ect. From what I've heard it's Hyd. Lifters too. Would 5.7L heads work on a 305??? The more opinons I can get 2nite, the better so that I can talk to em if you all think it might work.. Thanks

 

I can tell you that the heads would cause too much of a compression drop. 305 heads are 55cc I believe. Most stock 350 heads are in the 72cc range.

 

It may be worth looking into IF:

You had a 350 block you wanted to use everything on, and emissions was not a concern. Heads probably have too large a combustin chamber to use for your 305, no emissions on the intake (nor would the cam be deemed "emissions friendly" in most cases. Also, if it did come out of a boat, it was probably run at WOT most of it's life.

There's other concerns with salt water (and fresh water) corrosion that need to be taken into account.

I'd say if you're planning to use it to upgrade your 305, ditch the idea and look elsewhere. If you plan on using it to support a 350 and you're able to ascertain things are good that you need, then proceed cautiously.

 

The cam may be good. My father has a 305 marine motor in his boat, and it makes 235 horsepower. His boat hauls. This is with a 305 and a carbuerator. COmpression may be too low, but that cam may be useful. Too much work to bother with IMHO

 

Ya, your right there the 5.7 Merc. has a larger bore.. For some reason I was thinking it might have used a different piston.

Hey 8Mike9, the nice this with this engine is it has bot been run for more than a couple min.

I'll have a look over it, and see what there could be.. Thanks Guys.