283 sb chevy

Hi I have a chevy 283 out of a car I would like to put this in a boat, I have not done this before. I am fairly competent and can work my way through most situations. What manifolds will I need to make this work? Also how will I connect it to the outdrive and which outdrive will work? Any help would be greatly appreciated.

 

Oh dear not again . This has been hammered out over and over. Ktw1123-- please go to the thread 'Auto engine marinisation' Oh by the way,-- welcome to the forum!!

South Carolina? I know where that is --its kinda south west north America?

 

The long and short is auto and marine engines may look similar on the outside but they are very different as are there functions. A good comparison is take your auto engine and rev it at 4-5000 RPM's all day- see how long it lasts, thats what a boat engine does. You also have corosion, fire measures etc. Good luck! Might be cheaper/ easier to find the proper motor.

 

Here we go again.

Since GM uses the same bearings, crankshafts, rods, and pistons in their marine engines as their car engines, strength isn't the problem. A car engine will last just as long as a marine engine.

There are issues with corrosion and enclosed engine spaces, but not strength.

 

Marine engine 101:

1. Marine engines are generally based on automotive blocks. Up until the late 80's it could have been a Chrysler, Ford, or GM block. Newer engines are almost all based on GM blocks. That is basically where the resemblance (other than outward appearance) ends.

2. Marine engines usually run at much heavier loads than automotive engines. Auto engines run up to speed, then the tranny shifts and the RPM drops. A car cruising on a level highway at 60 mph is running at about 2500 rpm (depends on the rearend). lots lower than it's max torque, and using about 20% of it's rated hp. A marine engine at 3/4 throttle is running anywhere from 3500-4000 rpm or more (depends on the engine, prop, reduction gear in the transmission) and near it's max hp. It is generally running at or near max torque. So the loads placed on marine engines are much higher and so they must be built to handle heavier loads.

3. The cam is designed for heavier loads. Whereas in a car the cam is selected for general use over a wide range of rpms, the cam in marine engine is selected for max rpm and torque.

4. ROds, pistons etc are heavier.

5. Because they run under heavier load they need more cooling water. So the water passages are larger in a marine engine.

6. Valves are generally heavier duty like in trucks.

7. The head is usually heavier with larger water passages.

8. A higher capacity water pump

9. A higher capacity oil pump

10 Carburetor. The carburetor on your car and on your boat look the same but internally they are not. If the float sticks in the bowl and fuel flows out the vent on a car it goes out of the carburetor. On a marine carb it goes down the throat. Marine carbs are not allowed to spill any fuel into the boat. Plus that marine carbs have different jets and setup because of the reasons above in #2. Carbs also have to be fitted with a flame arrestor. There are flame arrestors available that both prevent back fires from igniting fumes, but also act as a filter. But most only act a a flame arrestor ( also called a backfire flame arrestor) FOR FUEL INJECTED SEE MY NOTE AT THE END

11. Marine engines use electrical wiring and equipment specifically designed to operate in a moist environment. Starters and alternators are sealed, or have flame screens to prevent sparks from igniting any vapors that may be in the engine compartment. So even the spark plug wires and caps are different.

12. Cooling can be raw water or closed cooling. Raw water is picked up by a through hull routed through the engine and then dumped into the exhaust generally where the riser exits to the exhaust line. Closed cooling uses a radiator much like an auto.

13 Some marine engines use a dry exhaust. Not seen much anymore.

14. Most marine engines have an exhaust manifold that has a riser on it that lifts the exhaust up through essentially a p-trap arrangement. This is to keep water out of the engine. Water will back flow through a marine exhaust system. The riser keeps it out of the engine. The height of the riser depends on the engine and where the water line is (How far below the waterline is your exhasut)

15. Fuel pumps on a marine engine must be designed to not leak fuel into the boat. Many are double diaphragm. Today most engines have electric fuel pumps. The pump must be mounted on the engine or withing 12 inches of the engine. This minimizes the amount of fuel line that is under pressure. It also means that unlike newer cars the line from the tank to the engine is under negative pressure. In other words the fuel is sucked to the pump rather than pushed to the pump. That way if there is a leak the engine just starves for fuel and stops. The pump must be fire resistant.

16. Fuel lines from the pump to the carb must be metal or USCG Type A marine fuel hose. This hose is fire resistant. The hose from the tank to the pump can be USCG Type A or B. B is not fire resistant and is hard to find.

17. Fuel filters can not leak into the boat either and must be fire resistant.

18. Fuel tanks must also be fire resistant and pass a 3 PSI pressure test. Today most fuel tanks on gasoline power boats are aluminum or plastic (Polyethylene) both pass all the requirements of the COast Guard. Other materials are not prohibited but need to be built to specific standards The tanks must not be integral with the hull.

15. The fill and vent hose can be USCG type B hose but again it's hard to find. You can use Type A.

HOWEVER: As Stonebreaker said, GM engines use some of the same parts on both the auto and marine versions. So go from there. I would add one amendment to this. If this is a fuel injected engine you have a problem. Most fuel injected auto engines have a pump in the fuel tank that then pressurizes the fuel lines. You don't want pressurized lines running through your boat so you can't have the pump in the tank. On boats the fuel pump is near (within 12 inches) or on the engine and fuel is sucked to the engine rather than pushed. However, A time delay is allowed, By this I mean that on most marine fuel injected engines, when you turn on the ignition the electric pump comes on and pressurizes the short fuel line from the pump to the engine, then it shuts off, until the engine starts then the pump comes back on. Most marine fuel injected engines do not have a pressurized return line to the tank. They have a built in recirculating tank on the engine, and a gravity feed back to the tank.

SO if you can live with that go for it. Have fun.

 

A car engine will last just as long as a marine engine

I agree 100%

283 was a good engine in its day. It was used in a lot of the early dragsters.It has the short 3 inch stroke and is capable of very high RPM's with the right components. It was also used in marine applications in the 60's and the head castings are much heavier than what is available today. But to use it for a boat, you got some work to do if you want it right. A lot of info is available in another trend as mentioned above. One thing that I havn't seen brought up is the distributer. For car engines, the advance curve is different and it has a vacuum advance. For marine, the advance curve is different with no vac advance.

 

Thank you!

Thanks for summarizing this. A few days ago I registered here to ask the same question. Did some searching and found the Marinization of car engine thread first. I got through 3 or 4 pages of posts until I quit. There is what, 12 or 14 pages on that thread?

So thanks Ike and others for taking the time to reply to this thread also. I think it has made my mind up to just get a decent marine replacement engine for the boat I bought.

Honestly going through the other thread I didn't know what to think. Half the people say "Sure, not problem just a few mods to make" while the other half say "No way, too much work, not strong enough engine, will cost more than a new one"

Just a suggestion from a 1 post new member but it sure would be nice to see a Sticky Topic that simply lists the pros and cons of marinising (sp?) of an auto engine.

I think it would save quite a few people a lot of time and it also might save some lives for those not patient enough to find out all the info before just dropping an unmodified auto engine into their boat, which is probably what I would have done had I not found this site.

Again, thank you!

 

I is certainly possible to marinize an auto engine, because most marine engines are based on auto engines. With a GM engine it's a little easier, but it does take time and money. It's all a matter of how much time you're willing to put into it, and how much you're willing to spend. If you do all the work yourself it saves a lot of bucks.

How much it has to be "different" also depends on what you are going to do with it. If it is going into a normal boat in an enclosed engine compartment, well then you're going to have to make sure everything is "marine". But if you take a look at HotBoat.com you'll see a lot of boats with engines that are almost all automotive, because they sit out in the open and aren't enclosed in a compartment. Those engines generally have a flame arrestor and Marine fuel systems, but that's about it. So it all depends.

 

Ike,

I have to disagree with your points 3 through 9.

3) Truck cams actually produce more torque than marine cams. Marine cams are somewhere between cars and trucks in torque and rpm production.

4) GM uses the exact same rotating assemblies in their marine engines as their automotive ones - check it yourself.

5) Same goes for blocks and heads - the blocks and heads are the same size, dimensionally, so there's nowhere to put bigger water passages.

6) Automotive valves are actually stronger than the marine ones, as they have to operate at higher temps. The current Ecotec 4 cylinder engine in the chevy cobalt, pontiac solstice, and saturn sky, for example, has sodium-filled, iconel exhaust valves. No marine engine has that.

7) Again, GM uses the exact same heads on the marine engines as they do on the automotive ones. There's no difference. None.

8) The marine water pump actually has less capacity than the automotive version, because it's designed to work in both directions of rotation.

9) Nope, again the oil pump is exactly the same.

Marine duty is harder on an engine because of corrosion issues. Somehow, the tougher corrosion issues have grown into a myth that performance duties are also somehow tougher on boat engines, which is completely untrue. It's commonly accepted that city driving, with its stop-n-go, slow engine speeds, and poorer cooling factors are harder on a car engine than highway miles, because at highway speeds there's more air flowing through the radiator, more oil circulating in the block, and more coolant flowing through the engine because the water pump is turning faster. It even says in your owner's manual to change the oil more frequently if you drive mostly in the city.

Yet a majority of a boat's operation is equivalent to highway miles on a car - higher engine speeds mean more oil and coolant circulation, resulting in less wear on the bearings and cylinder walls; and because a boat has access to water instead of air as the final heat transfer medium, the cooling capacity in a marine situation far exceeds the available cooling capacity in an automotive situation.

Research it for yourself and don't depend on secondhand knowledge.

 

Thank You all!

Just wanted to thank all of you for all of your help with this topic. After reading all the advice and ideas, I have decided to do the safest thing I could and have bought a Volvo Penta motor and outdrive. I do not want to put my life or any other boaters in danger. A fireman told me it takes a capful of fumes to blow a boat out of the water if it ignites. So I may still marinize the 283 but I am going to take my time and make sure it is right first.
Thanks Again to all of you, your input has been appreciated and considered. The life you saved may have been mine.

 

Very informative. I see there is so much to motors, and I think with my limited knowledge of marine applications I will do the right thing and spend a few more dollars on the marine setup.
Thank You.