Engine rebuild wish list

D

D. Andrews

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So I finally lifted the engine out yesterday and it is in the garage on the stand. Will start the teardown and rebuild once the weather turns wet and cold. So now it is time for the planning stage on what to do, and what to make better, thus the purpose in the post.

Engine is a 1989 mercruiser 7.4ltr (454) carbed with a Bravo I out drive. Engine has 164 hours on it. If you had the oportunity to not only rebuild but upgrade it what would you do? Here is what I am concidering:

Change out 4brl carb to 4brl TBI.
Upgrade cam to a slightly more agressive cam but not so much it makes it lope.
New distributer and ignition system.
Replace pistons, not sure on what to replace them with yet.
All bearings, not sure on manuf. yet.
Oil pump
Timing gear set
Of course all seals and gaskets
New starter
New alternator
All new sending units, and figure out why the low oil pressure shut down did not work
Check all wiring
Replace all external bolts to either brass or stainless.
Might replace raw water pump to newer style
All hoses and lines
Send heads to head shop for full rebuild and facing
Send block to block shop for facing, boring is still to be determined but I doubt it with as few hours it has.
Replace all cup plugs with brass, found a few that are carbon steel
Cap off mechanical fuel pump and replace with external electric fuel pump, still a bit iffy on this as I am not a fan of electric pumps in a boat.

So there is the short list, I am open for suggestions, recomendations, etc.........D.........
 
Wished he lived closer for sure! Would have made pulling it much easier with his nifty pulling rig.......D........
 
quote:
Originally posted by CurrentSea

Clean and paint bilge.

Click to expand...


Actually with in an hour of pulling it, poured the super clean to it and started pressure washing it. Will continue that today to prep it for paint. Got a lot of work to do in there while the weather still permits. Paint, wiring, water heater, battery boxes, the list goes on and on. Engine and drive will sit until the weather turns cold and wet............D.........
 
Change to electronic ignition system. How does a 1989 engine only have 164 hours on it?
 
Replace risers, manifolds and elbows
 
How does a 1989 engine only have 164 hours on it?

The PO bought the boat new out of seatle wa, hauled it to just south of the TN border and kept it in dry storage. They owned multiple boats and only used mine on a not very big inland lake. It sat in dry storage for several years due to them not having time to use it because of thier business demands, wife is a neuro surgon and he ran a high end catering business. When I bought it, it had 115 hours on it, and had some issues from sitting so long, but it did get serviced every year even if it never went into the water, what they didnt do was service the dry roting conditions of belts and hoses from sitting. I have the maintenance records that shows the details with the engine hours so I am fairly sure they are right.

Replace risers, manifolds and elbows

During the troubleshooting of the slightly high engine temp issue, the risers were pulled ( 6 weeks or so ago ) and they were in perfect condition other than a slight pitting on one of them, had them both ground and cleaned. Inspected the manafolds and they too were in perfect condition with no rust inside or out. The only visible sign of rust is right around the mounting surface where the paint chipped off. That being said, what would be the benifit in installing new one's?

Change to electronic ignition system.

Already has electronic ignition and appears to be factory. I am concidering upgrading that to an MSD or similiar system to add a little HP and better fuel burn...........D.........
 
this engine is NOT worn out.

should NOT need bearings, oil pump, etc.

has the CAUSE of failure been identified?

While the ER is empty, add lots of explosion proof LIGHTS to the engine room.

RWS
 
I remember the overheating but how did it get to the rebuild point??
 
Make sure you remove ALL the 'freeze plugs'.There are 1/2" plogs for the oil galleys. 3 threaded on the flywheel end and 3 small freeze plugs on the corresponding end. These are the main oiling galleys for the whole engine.Many people forget or don'r bother to do these.I've found some of these galleys completely plugged with debris.

There's also one vertical oil galley from the oil pump that goes up to where the oil pressure gauge or sending unit is attached. There is a plug halfway up that vertical galley that diverts the oil horizontally to port to the oil filter. If this vertical plug came loose, that could be a reason for low or no oil pressure. There is also another threaded plug just above the oil filter mounting point that can also be used as an oil pressure or sending unit mount. This return galley goes back to the vertical galley on the other side of the diverting plug. It continues up to a short diagonal galley that goes to the rear cam bearing. The rear cam bearing is the main distributing point for the rest of the engine. All these galleys should be cleaned out, especially if there is any problem with the oiling system that can't be found any where else.

As far as the rebuild goes and what parts to replace with what and how far to go with machining, that will have to be determined by what you want to achieve. By the year of the engine, there's a chance you have flat top pistons instead of dish pistons. Dish pistons were a design for smog control. What they accomplish, other than lowering compression, I don't know. What they DO do is prevent proper quench which actually prevents complete combustion which is counter to smog control. Computerized direct injection gets around the quench by the fine atomization of the fuel. The quench forces the fuel air into a violent swirl that exposes all the fuel/air to combustion.

The rest of a rebuild takes a lot of reading and learning about how your engine is built. Everything from calculating compression ratios to learning bore and stroke and deck height and even head gasket thicknesse's and how the alter compression and quench and what machining to achieve what. As an example, I have 325+ HP and 425+ ft/lb torque at 2500 RPM but was still designed to run on 87 octane all from a 1970 400 ci small block.
 
New plugs of a heat range for the TBI and Electronic Ign. You may have to change valves too.
 
Did you get this engie hot and burn it up? This list is for a 3500 hour engine.

At 154 hours it's not even broken in,

BTW I have a REAl good deal on a bridge in New York state.

Upgrade cam to a slightly more agressive cam but not so much it makes it lope.
New distributer and ignition system.
Replace pistons, not sure on what to replace them with yet.
All bearings, not sure on manuf. yet.
Oil pump
Timing gear set
Of course all seals and gaskets
New starter
New alternator
All new sending units, and figure out why the low oil pressure shut down did not work
Check all wiring
Replace all external bolts to either brass or stainless.
Might replace raw water pump to newer style
All hoses and lines
Send heads to head shop for full rebuild and facing
Send block to block shop for facing, boring is still to be determined but I doubt it with as few hours it has.
Replace all cup plugs with brass, found a few that are carbon steel
Cap off mechanical fuel pump and replace with external electric fuel pump, still a bit iffy on this as I am not a fan of electric pumps in a boat.
 
Check price for new crate motor.
rebuilding may cost more the a new one.
If you do go to fuel injection you will need a electric pump.

Tom
 
I now own my first fuel injected motor and will NEVER go back to a carb motor.

Might be something to consider
 
I wouldn't go too much cam. If you have access to a dynamometer I would pay the extra bucks to have it run in on one. Eliminates any issues with leaks and you can get your timing set perfectly.
 
Sorry for not responding to all the questions and remarks sooner, been a bad couple weeks at work, 14 to 16 hours a day and no day off. Been rough. So here we go:

this engine is NOT worn out.

No, not by a long shot, but......

should NOT need bearings, oil pump, etc.

Yes, yes it does, oh boy does it.

has the CAUSE of failure been identified?

Yes, since I have owned it, the oil pressure guage has always jumped while driving. Figured a bad guage or loose conection, maybe a bad sending unit. During a run, it went to zero, did not think much of it, and the engine did not shut down, figured it finally failed. Wrong. The oil filter return line burst and it dumped all the oil into the bilge and side of the engine room. Shut it down once I realized something was wrong, added a gallon of oil and started it up. Shut it right back down and called for a tow. Replaced line and the engine sounded fine at the slip. Took it out and once I started to throttle it up it became apperant that I had spun at least one bearing, and colapsed a few lifters. Back to the slip and out of the water she came. Engine is now in the garage on a stand. going to find the reason the low oil pressure shut down did not work as well.

Did you get this engie hot and burn it up? This list is for a 3500 hour engine.

No, never over 200, ever.

At 154 hours it's not even broken in,

Not broken in, but currently broken.

BTW I have a REAl good deal on a bridge in New York state

If the price is cheap and I can make money to pay for the rebuild, I am in. Not sure what this has to do with the rebuild though, but what the heck, I have money to invest.

Check price for new crate motor.
rebuilding may cost more the a new one.

True, but why is it a crate motor, what was wrong with it, who rebuilt it, what did they really replace, did they replace with quality parts or the cheapest they could find? Those are just a few of the questions I would have. I would rather do it my self, using the best quality of parts and do it right. At least even if it costs more, I have peace of mind knowing it was done right. Plus, I will probably go electric pump, but it really is not necessary, the system I am looking at is fully compatable with the oem original mechanical fuel pump.

I now own my first fuel injected motor and will NEVER go back to a carb motor.

My thoughts exactly. And probably what I will do.

I wouldn't go too much cam. If you have access to a dynamometer I would pay the extra bucks to have it run in on one. Eliminates any issues with leaks and you can get your timing set perfectly.

I do have access to multiple dyno's, and will probably do just that. I think it is well worth the time to run it out of the boat and get the bugs worked out prior to install. Still on the fence on the cam, might go more, but more intrested in fuel savings then HP increase. Never really had a power problem.

Now back to the original question. So now it is time for the planning stage on what to do, and what to make better, thus the purpose in the post.................D..........
 
My definition of a crate motor is a brand new engine not a rebuild used one

Good luck
Niles
 
I would do very little with the engine internals. You really don't want to try to build horsepower on a marine engine like this. It's pretty hard to improve on the package of piston/head/cam that comes in the typical chevy marine block. Possible, sure but you will spend a lot of money with very little return. I financed my education in this area once with a very we'll respected machine shop with a very we'll meaning owner. I wound up with an engine that might have been well suited in a race car, but rather marginally performed on the water. GM engineers know very much about putting together reliable engine cores suitable for high torque needs. Put your money elsewhere for greater impact.
 
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