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Pulling a bad engine, changing to EFI?

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BenSmith

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I’ll save everyone the time and headache over the mess of a story that I’m in and I’ll make it short.

Engine block is cracked in a 1979 mercruiser 228. It’s carbureted and is a Chevy small block 305 marine variant.

needless to say, that engine will be coming out and I’ll probably part it out or save parts and pieces of it if I decide to grab a 350 small block and bolt all my marine hardware on.

I have found a complete mercruiser 5.0. It’s a late 90s model and is electronically fuel injected. Seller sent me a video of the engine turning over and said if I made the drive to him he would be sure that I see the motor running before I left with it if I decided to buy it.

one big advantage of this 5.0 is that it has closed loop cooling system

would this EFI engine be plug and play into my old (‘78) dash?
if needed where could I get a new harness/dash cluster?

Ive never pulled a carbureted engine in anything and swapped it with an EFI engine. Any advice is welcome, and the only reason I’m considering doing this swap is that the complete EFI running engine is $400 and has already been pulled from a boat with a destroyed transom.

will my shifter/throttle? Need to be replaced?🧐🧐
what needs to be replaced....?🧐
 
It's more or less a straight swap. The existing multi plug should fit into the "new" engine's. You can use the existing controls and cables. Plumbing for water is about the same except for the seawater supply hose. I believe that you'll need a longer one to reach up to the heat exchanger. Use Shields brand hose.
The main difference will be the fuel plumbing. You'll need to rig a return line to the tank(s).
Honestly, a $400 price tag on a complete closed cooling 350 seems far too good to be true, so I would have the engine gone over by a professional before bolting it into anything that I would be taking any distance from the dock more than I could swim back.
 
I think You'll need a coupler like this since your original engine is a two piece rear seal vs the newer one piece rear main seal https://www.michiganmotorz.com/mercruiser-hub-style-coupler-1986-later might be worth a call to somebody like michigan motorz who does a lot of repower work to pick their brains as i dont know if you need the older size 12.75” flywheel vs the 14” that will be on the newer engine

also need to use the flywheel cover off the old engine on the new one as the rear motor mount spacing is different on the older transom housing.

the exhaust on the newer engine will be center riser vs the older log style you'll need to make sure you have the down elbows and rubber boots to connect to the existing wye pipe.

as O2 mentioned thats a hell of a cheap price for a complete drop in. Id run it check the oil pressure with a mechanical gauge, check compression, and verify no water is in the oil.
 
If the "new" engine was run in sea water, I'd save myself some trouble and consider replacing the exhaust elbows .... hopefully MERC "dry joints".
 
No return line to the tank is needed. Mercruiser EFI/TBI systems dead head at the throttle body.... FYI the 5.0Ltr engine is a real POS.... Keep looking until you find a 5.7....

Going from a 5.0 carb to a 5.0 efi is not a forward move, it is not a lateral move.... Remember you are buying a 21+ year old obsolete MEFI system.
 
BenSmith said:
I’ll save everyone the time and headache over the mess of a story that I’m in and I’ll make it short.

Engine block is cracked in a 1979 mercruiser 228. It’s carbureted and is a Chevy small block 305 marine variant.

needless to say, that engine will be coming out and I’ll probably part it out or save parts and pieces of it if I decide to grab a 350 small block and bolt all my marine hardware on.

I have found a complete mercruiser 5.0. It’s a late 90s model and is electronically fuel injected. Seller sent me a video of the engine turning over and said if I made the drive to him he would be sure that I see the motor running before I left with it if I decided to buy it.

one big advantage of this 5.0 is that it has closed loop cooling system

would this EFI engine be plug and play into my old (‘78) dash?
if needed where could I get a new harness/dash cluster?

Ive never pulled a carbureted engine in anything and swapped it with an EFI engine. Any advice is welcome, and the only reason I’m considering doing this swap is that the complete EFI running engine is $400 and has already been pulled from a boat with a destroyed transom.

will my shifter/throttle? Need to be replaced?🧐🧐
what needs to be replaced....?🧐
Click to expand...



ok guys, first let me say thank you for taking the time to reply to this thread with all your advice. I’ve made a mistake about the replacement engine I found.

it is a late model, however, it isn’t fuel injected but it does have the electronic ignition. The thunderbolt IV.

When talking to the seller he was able to send me a video of him jumping the starter with a battery, in the bed of an old pickup truck..

the story is “he just sells engines he’s not a boat guy” anyway, whatever.
he assured me that if I made the 4 hour drive he would have the engine running before I left to ensure it’s running.
I plan on looking over the block really well, doing a compression test, seeing it running, checking the oil for residue and water multiple times, inspecting the coolant/antifreeze and that would about sum it up considering it’s not installed.

my old engine would then be just a parts engine to keep the other one going for a while.

I know a 305 5.0 isn’t the greatest motor but for a direct bolt up for $400 I can’t complain as it will get me on the water in a few weeks for a day or two weekend job. everything is null and void if the replacement doesn’t work. In which case I might as well search for a small block pulled out of a truck 🧐

given all the available options I may even consider building a small block in the garage for a later swap.
 
An abbreviated version of my current boat - I got it cheap off a guy nearby. He knew the block was wrecked and I didn’t pay much for it. It did come with a BRAND NEW trailer 2020 model. The boat is over 22 ft - fiberglass deck boat...
New starter, brand new bellows, still have the stickers on them and I plan to pull them off my current motor and use them on the “new”. As for the exhaust manifolds, risers etc etc I’ll pick the ones in best shape
 
Don't waste the 8 hour round trip. Even a tired out POS with a cracked block will start and run so that's not really any kind of test. Plus, it's probably not a marine engine.
Your best course of action is to get a remanufactured short block and move the components from the bad engine over to the fresh engine. It will come with a warranty, customer support and you'll get on the water just as fast as buying from Billy-Bob.
Let's establish that boating is not a cheap hobby, and the LAST thing you want to shave pennies on is the engine and drive. Are you planning on taking guests and family out on this thing? Then you better have your gear in order, that's all I'll say.
Here is an example of a rebuild engine from a very popular vendor. As you see, it's not horribly expensive to have reliable power. You were gonna spend 400 plus another (equivalent to) 800 on transport plus all the hoses and gaskets and new pump and your time and labor and blah blah blah. That would be only a few hundred less than just getting a fresh engine.
https://www.michiganmotorz.com/5-7l-350-ci-marine-engine-1987-95
 
I agree with o2. Lots of risk with used motors in anything.....especially a boat. The 305 motor is just a reduced bore 350, (5.7). I suggest play carefully, spend some money.....if the boat is nice condition, make sure you have corrected the problem that caused the crack. Chev blocks of this era are prone to crack just above the lifters. I have found no specific reason for this except that GM created thinner castings and possibly threw "caution to the wind", when allowing blocks to be built for marine and high performance or severe duty applications. This involves nickel and tin contents in the cast iron formula, but more specifically "core shift". I have to say that many do not understand core shift in cast blocks and how to check for integrity. A regular automotive block may pass, but a block destined for marine, fleet, or high performance must meet specific measurements.
At a risk of longevity and just to make a buck, some builders don't effectively evaluate blocks before they are built.
 
as far as EFI vs carbs in older boats, I vote for carbs. You can start new for a minimal investment (new pump either mechanical or low pressure electric) and a new carb either Edelbrock or Holley. You won't have to worry about sourcing NLA Merc sensors, ECMs or other EFI parts which is a real problem on older throttle body and EFI boats from both Merc and Volvo. Thanks to the classic car/muscle car aftermarket, carbs and electric pumps are very easy to find, just use ones rated for marine use. The only advantage of EFI is smoother cold running due to better mixture control vs a carb. Other than that, there are really no significant advantages. Repairs are much cheaper with a carb. You can buy the best rebuild kit there is for approx $50. A low pressure electric pump is usually less than $200. Mechanical pumps are even cheaper, I got a Carter mechanical marine pump for my OMC 4.3 for around $85 from Summit Racing. Yes they sell marine pumps if you know what parts # you are looking for.
 
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