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page454
11-03-2006, 09:34 AM
I just bought an 88 Donzi off of ebay and picked it up yesturday. I bought it with a seized up 5.7L engine. My first question is, is there anything different between this engine and a chevy 350 in a vehicle. I'm new to boats but I am a certified mechanic with a lot of history of small and big block chevy's. Is there anything I need to know before I swap the engines. I have a 300hp 355 engine that is fresh and was going to go in a race car but I opted for a 383. Also my other question is where can I get more information on these donzi boats online, besides this website? The link to my boat if anyone is interested is http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=014&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=330036393744&rd=1,1

MOP
11-03-2006, 11:27 AM
Yes!
Pistons should be Hypernetic or equivilant
Bearings
Good idea to have atleast S/S exhaust valves
Brass core/freeze plugs
Circ pump has S/S guts and back plate
Carb, starter, altenator and fuel pump are marine.

The are put together with stronger parts to withstand the constant load that an auto does not have to put up with.

Phil

MOP
11-03-2006, 11:31 AM
Qoute: The link to my boat if anyone is interested is http://cgi.ebay.com/ebaymotors/ws/eB...6393744&rd=1,1



http://www.donzi.net/dlist/ Scroll down to Ragazza they were 17 to 25 feet, we have several members with them.

Phil

Carl C
11-03-2006, 11:46 AM
You have found the definitive site to help you with your project. Others here have much more experience than I and I'm sure they'll pipe up. You'll want to select a camshaft made for a marine engine. You'll also want to beef up the valve train. Remember, your motor will probably never see over 5,500 or so RPMs. If you use a cam that peaks at 6,500 or so than you will end up with a real dog and may suck water into the motor. The carb and alternator are also different. Hopefully you got all those items with the boat. Welcome to the only boat site you'll ever need!

Formula Jr
11-04-2006, 06:55 PM
Page, as someone pointed out to me the other day, eBay now restricts viewing past auctions, so I don't know what kind of 18 you bought.

The car engine in a boat debate has been played out here several times.

You have a 355 Chevy Auto engine you are considering putting in a boat.

It comes down to where you want to go boating and if you want or can get your insurance carrier to sign off on it. And insurance companys will find any reason to reject a claim if you have a fire or "BOOM." . A certified marine engine already has everything done to it safety wise.

At a minimum you'll need to consider the fire hazards involved with boats that cars don't have. The big considerations are spark/flame control and how gasoline is contained.

My list isn't exhaustive, it's just whats at the top of my head:

Spark/Flame Control:

Alternator
Carb Flame Arrestor, boats don't have air filters.
Carb
Starter motor and selenoid
Distributer
Voltage Regulator. And any type of relay.

These all NEED to be Approved Marine.

Gas containment:

Fuel pump
Gas lines
Carb Float Over Flow.

These also HAVE to be Approved Marine.

Treatment of the short block isn't that important if you run a freshwater cooling system and have a mild cam. With out freshwater cooling you have a bit more work to do.

Where you boat:

Most marine engines are designed for reliability over performance. If a car engine quits, you roll over to the side of the road and call AAA. If a boat engine fails, you are in a whole lot of hurt, unless you are on a small lake.
So boat engines are designed conservatively.

Lenny
11-04-2006, 08:32 PM
Aaaahhh, at 205 ponies, isn't it a 5.0 litre(305)?

Yes, there are many things that make a marine motor a MARINE motor. i think ring placement and end gaps are different too.

page454
11-05-2006, 10:35 AM
Thanks for all the replies. Fortunatelly I still have the old engine with the boat so I have a starter, alternator, and whatever else to keep this boat safe. My 355 does have hyperutectic pistons and moly rings so I should be safe there. If anyone else has anything you think I should know please post or email me at page454@hotmail.com I greatly appreciate it.

-Page

BigGrizzly
11-05-2006, 12:11 PM
Just a note I would not use Hypereutectic pistons in a boat. I know people do but the rings have to have a larger gap to survive.If you race cars you know the pistons are used for claimers because there cheap. Forged is my only suggestion. BTW this is not up for discussion because I have done this too many times on D net.

zimm17
11-06-2006, 01:50 AM
Are you going to run fresh or salt water?

Make sure you have a marine carb or you risk blowing your entire boat and yourself up if you have a backfire with fuel fumes in the engine compartment. Flame arrestor too.

Make sure you have brass freeze plugs in the block.

Make sure you upgrade to a marine (mercruiser) water pump if you plan any salt water. Fresh water you'll get a few years out of an auto waterpump.

Make sure you have a good low end torque cam preferibly a marine cam, if not at least a RV or truck type- you'll be cruising around at 3000rpm mostly with around a 5100 rpms redline.

Other than that, your existing engine should work just fine.

page454
11-06-2006, 09:13 AM
I'm going to only be in freshwater or at least that is the plan. I will still probably use a marine water pump and make sure to have brass freeze plugs in the block. I also am thinking of running an edelbrock tunnel ram intake and dual carb setup that would be sticking out of the engine compartment on the boat. I already have it and it would at the very least make the setup safer in case of a backfire. What do you guys think?

-Page

Carl C
11-06-2006, 11:55 AM
Well I'm not the resident marine sbc expert but I think that would be too much and your secondaries would probably never open. You need to maintain intake velocity. Also marine engines tend to run lower comp ratios (under 10:1). And don't forget the high capacity oil pan. Just my 2 cents. Good luck.

page454
11-07-2006, 03:27 PM
The carb setup I am thinking of running are predator carbs, which don't work like conventional carbs do. These carbs are specially designed to only use as much fuel as the engine needs, also eliminating tuning the carbs for specific engines. I do have a high capacity oil pan, so I'll use that --Thanks. Anyone else have an opinion.

BigGrizzly
11-07-2006, 04:27 PM
Good luck with the preditor let us know. I havn't had good luck with them in the marine use.