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Rebuild question

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805HD

Regular Contributor
So I’ve decided to rebuild my engine, for no other reason then piece of mind. Got a ‘87 cobalt with a 454 and alpha1. She’s a mature lady but she runs well. I pulled the engine and tore it all down, no signs of hot spots, cracks or anything like that. So things look good.

The plan is to have everything hot tanked, inspected and cleaned up. New rings, main, rod and cam bearings, valve job etc. Just want to freshen her up.

Ideally I’d like to find a shop to build me up a long block and I’ll just take care of the top end at home.

anyone have any ballpark figure on what that might run me?

Located in California
thanks in adavace
 
Shop rates vary a lot...and I'd expect CA to be on the high end....best to call around, or visit and ask.....sometimes its better to let them supply the necessary parts....and essential for the cam bearings unless you have the toolset.....

ballpark - between 500 & 700 depending upon what needs to be replaced in the heads....
 
If you put it all back together yourself it may be less but my estimate would be- $1500-$2000. If less then you have beer money!

A SHORT block assembled (no heads)/typically no oil pump or pan/no water pump and in some cases no timing chain cover.

LONG block assembly includes heads/push rods/rockers/oil pump/pan. All assembled. Best way to go. The rest is on you to assemble.

Heads alone will most likely run around $500 if done right.



Block should be decked, squared, honed, Crank reworked/massaged and properly balanced!! If they are good they will make all piston rods and piston assemblies as close to the same weight as possible........makes for a very smooth idle and very little vibration throughout the rpm range.

They will know if there is a need to be oversized bore or not and if so then new pistons/rings.

New rings even if no new oversized pistons. Complete engine Bolt kit. New Oil pump. Double roller timing chain with new sprockets, Engine gasket (Marine) kit. You may also need new push rods but they will make that call.

I am sure there are additional things to consider......
 
Ideally I’d like to find a shop to build me up a long block and I’ll just take care of the top end at home.
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Ayuh,...... I think yer gonna have a tough time findin' anybody to put it back together, without some machine work, 'n matchin' new parts,.....

A shop has to stand behind their work,....
That's tough to do on a 1/2azzed reman,.....
 
What do you mean the top end? You mean you want the shop to build you a short block, then you'll put the heads on yourself making it a complete long block? Are you going to let them redo the heads too?
 
Nothing like a pre-run (on a dyno) semi-broken in long block with a guarantee! May even be cheaper in the long run.

Jeff
 
Thread title says "Rebuild Question"
If you are wanting to simply clean things up and re-assemble (as a "freshen her up" w/ new rings/bearings/valve job, etc), this would be a re-furbish, not necessarily a rebuild.

805HD said:
So I’ve decided to rebuild my engine, for no other reason then piece of mind. Got a ‘87 cobalt with a 454 and alpha1. She’s a mature lady but she runs well. I pulled the engine and tore it all down, no signs of hot spots, cracks or anything like that. So things look good.

The plan is to have everything hot tanked, inspected and cleaned up. New rings, main, rod and cam bearings, valve job etc. Just want to freshen her up.
Ideally I’d like to find a shop to build me up a long block and I’ll just take care of the top end at home.

I'm sure that you could find a shop who would hot-tank your components, clean things up and check for cracks, etc.
However, I think that you'd be hard-pressed to find a shop who would be willing to offer any type of warranty under those conditions (i.e., an assembled short block while re-using pistons, non-reconditioned rods, existing cam, etc.)

I would suggest that you have the shop do an actual "rebuild" for you whereby they can offer you a warranty.
If need be, go first over and with new pistons and fully reconditioned rods, turn or polish the crankshaft within specs, new camshaft, etc.

If you go with inexpensive pistons, you're looking at spending around $250 or less (you'd be buying piston rings anyway)
If you go with a good Hypereutectic alloy piston set, you're looking at spending a tad bit more.

A new Marine BBC flat tappet cam and cam followers will cost you about $200 or perhaps a bit less.

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All valid points.. and yes I would have the heads done as well...

anyone have any recommendations on a good company to get a short or long block?
 
anyone have any recommendations on a good company to get a short or long block?
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Ayuh,........ Try here,.....

A used motor in a rotten boat might be a cheaper option,..... a donor boat,... scrap, or trash what's left,....
 
805HD said:
All valid points.. and yes I would have the heads done as well...

anyone have any recommendations on a good company to get a short or long block?
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If your engine is in good condition I would use that. No need to purchase a second one.

If you do your research in your area try to find a shop who does performance engine building and as suggested, possibly has a dyno to pre-run and tune the engine.

Purchasing a standard off the shelf short block has no advantage in your situation. If your engine block was bad then yes but because if is fully operational, going to a reputable shop and having it "freshened" up is the right direction to go..

NOTE: because you have an ALPHA drive you have a limit on power. even OEM 454 power levels (torque) have that drive at its maximum capability level.

So you MUST keep the torque of the engine at its OEM level. I am surprised the drive has lasted this long!
 
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I will go the opposite direction here. If you like this boat and want to keep it, I would go to your friendly neighborhood Mercruiser dealer and look into a new power/drive package. Yes it will be a load of money but they will finance it and it might be more affordable than you think. Definitely go find out what they can do for you.
Get new controls and gauges while you're at it.
It will start and run flawlessly, give you more speed and lower fuel consumption, have warranty, be serviceable by any mercruiser shop, blah blah blah...

If you rebuild you'll be into it for several thousand, and still be right where you were before doing all the work/spending the time. A whole new everything will allow you to get out on the water sooner with far more peace of mind than your rebuilt lump and 30-odd year old drive. As others have said machine work is expensive and rebuilding an engine is far more costly than simply buying a rebuilt long block from a remanufacturer. It's about 3500 for a off the shelf rebuilt 454 long block. Your machine work alone is going to be in the 2-2500 range and then there's parts. They will charge you retail plus premium at the machine shop.
 
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o2batsea said:
I will go the opposite direction here. If you like this boat and want to keep it, I would go to your friendly neighborhood Mercruiser dealer and look into a new power/drive package. Yes it will be a load of money but they will finance it and it might be more affordable than you think. Definitely go find out what they can do for you.
Get new controls and gauges while you're at it.
It will start and run flawlessly, give you more speed and lower fuel consumption, have warranty, be serviceable by any mercruiser shop, blah blah blah...

If you rebuild you'll be into it for several thousand, and still be right where you were before doing all the work/spending the time. A whole new everything will allow you to get out on the water sooner with far more peace of mind than your rebuilt lump and 30-odd year old drive. As others have said machine work is expensive and rebuilding an engine is far more costly than simply buying a rebuilt long block from a remanufacturer. It's about 3500 for a off the shelf rebuilt 454 long block. Your machine work alone is going to be in the 2-2500 range and then there's parts. They will charge you retail plus premium at the machine shop.
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Ditto.... I've reengined two boats and was planning the re engine of a third when I had to sell it ( divorce). All three times, when I did the cost /benefit analysis including my time and warranty issues ( in your proposed scenario you have none!!) I ended up buying a new factory crate engine... since I run in sea water, I ordered them with the "Fresh" water cooling kits.
 
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