Buddy of mine has a 330/7.4 now. After asking questions in another thread he has decided that a drop in crate motor is going to be the best option. I know most people say that car engines won't work in a marine application but was wondering if you guys would look at these links and see if these engines would work for him. I don't know anything about BBC's so please let me know if the cam specs look ok. Also wondering if his current flywheel will bolt up or if he will need a new fly wheel. He is running short risers so I need to know if reversion will be an issue with any of these. Thanks guys.

http://www.summitracing.com/parts/NAL-12568774/

http://www.summitracing.com/parts/NAL-12568778/

http://www.summitracing.com/parts/NAL-12371204/

I've got one of the 454 ho 425's for sale, was in a boat and have seen several installed in marine apps, but why not buy a long block from a marine builder? or a low hour used complete ?

You may save a few thousand but you get NO warranty if you put it in a boat. Just something to think about - if I had a brand spanking new crate motor I would be damn sure I had a warranty. Also note that you want to make sure the the internals in the engine you buy are forged. And, I saw you were looking at some short blocks - I do not think that your carb and intake off of the 330 HP 454 will get you the HP you need out of these motors so you are going to have to get those also. Just my newbie 2 cents - take it for what it is worth!

How about something like this. http://www.offshoreonly.com/classifi...o46889-en.html. I do not know the builder or their qualifications but it seems to me this would be a whole lot easier and likely cheaper in the long run.

Looking at those also, just don't know anything about them

if your buddy has a 330/454 its just a plain ole car/truck engine with cast internals..
the mags have forged gm parts same as the gm HP crate engines
only merc engines that are special are the blue ones..
put brass freeze plugs and the correct filter bypass on any GM crate engine
and you magically have a stock merc engine..
Merc does NOT build any of the black engines themselves, you can buy the same thing yourself from gm and remove the middleman..

The zz motor comes with the heads and intake off so u can choose your own gaskets and what not. But it is a complete long block just needs the top end bolted on.

By biggest concerns are the flywheel and oil cooler. Will the flywheel from the 330 work or will he have to buy a new one? I'm not familiar with oil coolers either so if somebody could point be in the right direction that would be great.

Oh, the bypass Spring is another thing I was wondering about is that changed internally or externally?

I believe you stated earlier it was a 1990 which would be a Mark IV. They use a 2-piece rear main seal. These all use a 1-piece rear main seal so the cranks are different so yes you would need a flywheel. There would be the possibility of reversion with any of these cams especially the ZZ. Exhaust is one of the first things you need to upgrade if you plan on making other improvments. If he's set on keeping those exhaust then about all he can do is a mild cam upgrade, intake and carb.

He's looking at a set of emi thunder manifolds with the aluminum riser, more than likely the 502 HO is what he will use. Will that cam work with short risers or will it still require a hi perf riser?

I just bought EMI's for my 454 mag and they said if there is any kind of cam work you really needed to go with the stainless risers.