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To rebuild or buy a longblock??????

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Rshaw450

New member
Hello everyone.

It all started with a leaking oil pan yesterday. No sooner did i pull the pan off that i found the dreaded creamy oil and a few piston fragments in the pan. I am going to continue tearing the engine down to see the extent of the damage but i am optimistic the cylider walls are clean. There was no top end nosie what so ever. If i can figure out how to add pictures ill add some from yesterday.
 
It would be very helpful if you were to let us know which engine you are asking about!
GM, Ford, Winklehouser, Hergamartin, or one of Doc Brown's 1.7 jigavolt units! :D

If if by chance it's a SBC, I would definitely do a custom rebuild for reasons that we can discuss later!



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i did nt know they came with a flux capacitor.
RicardoMarine said:
It would be very helpful if you were to let us know which engine you are asking about!
GM, Ford, Winklehouser, Hergamartin, or one of Doc Brown's 1.7 jigavolt units! :D

If if by chance it's a SBC, I would definitely do a custom rebuild for reasons that we can discuss later!



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It's always cheaper to buy a block from a remanufacturer than to have it rebuilt by a machine shop. You get a warranty and it will usually show up in days, not weeks (or months). Sometimes you have to return the core, sometimes not depending on who you buy from.
 
Rshaw450 said:
If i can figure out how to add pictures ill add some from yesterday.
Click to expand...
When you respond to this thread you will see a little square icon that looks like a picture of a tree. That's the add image button. Click on it and follow the instructions.
 
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o2batsea said:
It's always cheaper to buy a block from a remanufacturer than to have it rebuilt by a machine shop.
You get a warranty and it will usually show up in days, not weeks (or months).
I would agree.
However, I have asked the OP to let us know which engine he is asking about.
RicardoMarine said:
If if by chance it's a SBC, I would definitely do a custom rebuild for reasons that we can discuss later!
Click to expand...
If Ford or BBC, I may not have asked..... but if he has a SBC, there are some definite Dos and Don'ts that the average production Machine shop turns a blind eye to.
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I cannot believe i left out the most important information. It is a 1993 mercruiser 5.7 350. I have worked at tearing it down and am fairly certain that it can be rebuilt without any big issues. Better pictures tomorrow.
 
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Ooooops.... that should have read:

If you were to buy a marine version SBC, from a reputable supplier, you'll more than likely get one with the GM Full Dished pistons! :mad:
 
I cant add pictures yet. I dont have privileges yet. So with this being a marine SBC, what are the dos and donts of the machine shop?
 
Rshaw450 said:
So with this being a marine SBC, what are the dos and donts of the machine shop?
Click to expand...

For me, the most important “don’t” would be DO NOT use the GM F/D pistons.

The most important “do” would be to use a Quench style piston with the correct quench dimension.

Please read the thread that I linked to earlier!



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Rshaw450 said:
I cant add pictures yet. I dont have privileges yet. So with this being a marine SBC, what are the dos and donts of the machine shop?
Click to expand...

The cam shaft the machine shop uses is critical; as others said earlier if it's not specifically for a marine engine, it should be for a truck or RV.

Here's some stuff after the machine shop is done: Install a high volume oil pump, and the shaft that drives it needs to be the heavy duty version. Replace the harmonic balancer on front end of the crankshaft. Also replace the vibration dampener at the other end of the crankshaft, if your set up has one.
 
New member here, retired ASE Master automotive technician, just bought a 19' runabout with a Mercruiser 898 and was looking for a good source of reference data and advice.

I have to say, reading this thread, I am ecstatic to have found y'all, this info source exceeds my expectations! :)

No issues with the boat yet, it ran kinda doggy during the test drive but the gas smells like varnish so that's probably a clue. Its hitting all 8, idles smooth and quiet, so I figure to replace spark plugs (mainly to look at them and make sure they're the right ones), set timing, and run Seafoam and fresh gas through it and probably be done. The previous owner claims to have had a reputable local marine shop (Pensacola Florida, there's plenty here) overhaul this engine a hundred or so hours ago and it sounds tight enough that I believe him. (knock on wood LOL)

I was looking for the procedure to lock the ignition timing into base mode but I believe I found that (now just gotta go hunt down that connector with the Purple/White wire).

Dumb question - many years ago I owned a very similar 19' runabout with an Chevy inline 4 cylinder OMC sterndrive. I wanted it to pop up out of the hole quicker, so being a young guy who knew everything I did what I always did with outboards - I put a Doel-Fin on it. It helped the hole shot a lot. Now, I'm older and don't know as much anymore (LOL) I'd like advice from those that have more experience - is that a good idea, or not?

Also, I noticed during the test drive that unless you're trimmed all the way down, this thing porpoises like Flipper. The previous owner has a couple of small manually adjustable trim tabs on it, and they are set level with the bottom of the hull. Should a boat like this need to be trimmed all the way down, or do I need more trim, or what?
 
RicardoMarine said:
For me, the most important “don’t” would be DO NOT use the GM F/D pistons.

The most important “do” would be to use a Quench style piston with the correct quench dimension.

Please read the thread that I linked to earlier!



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Thanks for the link. Im going to look into the piston differences.
 
Rshaw450 said:
Thanks for the link. Im going to look into the piston differences.
Click to expand...

The differences are easily observed.

You will see the full dished style being used by GM and by the average marine engine builder.
This piston profile was introduced in the early 70s for the sole purpose of lowering the auto engine emissions.
One piston fits all eight bores, allowing an almost untrained person to install them.
The dished area, when positioned underneath the cylinder head's flat "quench" surface, gives the flame front a place to hide, often causing a secondary burn (detonation).
Ignition advance is held back in order to prevent this..... but this causes a loss of potential power!

SBC full dished piston by Sealed Power.jpg



A much better selection would be a LCQ (low compression quench), D-dish or Reverse Dome style piston that will "mirror" the cylinder head's quench surface.
These will require either 2 or 4 part numbers, and will require a higher level of expertise during the installation and build.
When assembled correctly, ignition advance does NOT need to be held back.
This allows the engine to achieve the desired LPCP causing it to produce more power and torque.

The Q/E is nothing new.
GM's first OHV V-8 (1955 265 cu in) incorporated a quench effect.
Chrysler enthusiasts have been using it for years.
 

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thanks Ricardomarine! I would like to attach pictures for all to see as I plan to make this a build thread but I cannot upload from my phone or computer.What web source do you all use? I appreciate everyone telling my to do a custom build but I simply cant afford the extra cash right now.

As for an update, I have the motor disassembled in my garage. When I can get the time from work I will be taking the block and the heads to the machine shop for any required machine work they identify as needed. I have been tinkering with the crank and cam looking for part numbers. the cam i think is a 022944???
Who sells a respectable rebuild kit? I dont know if I trust ebay.
And is there any where I can download a Electronic manual for this motor. I am a descent wrench turner but always like to cross my Ts and dot my Is.
 
Take the crank and cam in to the machine shop after you receive the bearings. Have the OEM specs so they can grind them properly. Take at least one connecting rod and piston rings as well. They can mic the crank and cam to see if they are within spec and can still be ground. Ring end gap and piston clearance are very important for marine engines. Be sure and plastiguage the main and connecting rod journals prior to final assembly.
 
kimcrwbr1 said:
Take the crank and cam in to the machine shop after you receive the bearings. Have the OEM specs so they can grind them properly. Take at least one connecting rod and piston rings as well. They can mic the crank and cam to see if they are within spec and can still be ground. Ring end gap and piston clearance are very important for marine engines. Be sure and plastiguage the main and connecting rod journals prior to final assembly.
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So i should buy a rebuild kit before dropping it off at the machine shop? Im new to going this in depth but im comfortable with it. I dont feel like its out of my abilities. I just want to have my ducks in a row. Thanks
 
So i should buy a rebuild kit before dropping it off at the machine shop?
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Ayuh,..... Go talk to yer Machinist before anything else,....

He'll offer ya some options, 'n you can bounce yer options off him,.....
He might well give ya a "Package Deal",......
He'll have several parts options, that might be better than yer's, 'n he can make a few cents on the parts, as well as his labors,.....
 
Just take your time the guys here will steer you in the right direction. Do lots of reading and ask lots of questions. You can allways start another thread and post lots of pics. Someone else can surely benefit from it.
 
@awculero you should start a new thread and ask your questions there instead of burying them in someone else's thread. As to your doel-fin question, if these things actually helped, manufacturers would be advertising how wonderful their fins were and they'd be standard equipment on virtually everything.
What these attachments do is act as a trim tab; keeping the bow down and helping get the boat on plane faster. Whether they actually do that is questionable as they are usually not set up properly and on a larger boat they may actually slow you down...a lot. Most sterndrive and outboard motor manufacturers specifically call out these devices and often will void your warranty if you install one.
As to your proposing problems, this can be due to many factors. First thing, remove any aftermarket trim devices. Use the sterndrive trim first. Also be sure the boat is not bow or stern heavy. You ay need to move some weight around.
 
Like most other guys are saying check with the machine shop first,it may need bored which obviously means different size pistons.There are several places to get rebuild kits like Jegs or Summit where you can go from mild to wild with many different companies to choose from depending on your budget.I just rebuilt my boat engine.A 3.7 four banger which is half of a Ford 460 and Summit racing had rings bearings,oil pump and most gaskets for this uncommon engine and it was only a bit over $100 bucks.Installed it and fired it up Saturday and dumping it in the water Wednesday.Good luck with your rebuild if you do it yourself,and better luck if you have the machine shop build it for you.Unlike a car you cant just pull into a parking lot if the motor goes boom and in a car you dont have to worry about rods punching a hole in the hull.
 
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Rshaw450 said:
DJR, the machine shop is only cleaning and doing a qa/qc on the block. Ill be building it myself.
Click to expand...
As Rob F says...... you will want to have your machinist verify that the cylinders are OK @ 4.000" or if they may required being cleaned up (i.e., bored first over)!
This must precede the ordering of pistons/rings.

Rshaw450 said:
thanks Ricardomarine! I would like to attach pictures for all to see as I plan to make this a build thread but I cannot upload from my phone or computer.What web source do you all use? I appreciate everyone telling my to do a custom build but I simply can't afford the extra cash right now.
The Quench style pistons will not break the bank.
Here is a 390 Hypereutectic alloy set for a standard 4.000" bore that will give you a S C/R of approx 9.6:1 w/ 64cc chambers.............. $299.99

Keith Black KB193.030 Dished 5.7 Rod Chevy 350 Hypereutectic Pistons
https://www.ebay.com/itm/Keith-Black-KB193-030-Dished-5-7-Rod-Chevy-350-Hypereutectic-Pistons/261865066944?hash=item3cf85fd1c0:g:5o4AAOSwDVtaYR4E

For S/B Chevy 350 c.i. (4.000" bore x 3.48" stroke).

  • 390 Hypereutectic alloy
  • Fully machined crowns and valve reliefs
  • Drilled oil drain backs
  • Full floating wrist pins
  • Triple wound spiral locks
  • Reflective alloy allows 2% power increase
  • Quench dome technology minimizes deterioration
  • Zero deck quench designs
  • Lightweight wrist pins

NOTE: the auction description data shows two (2) bore dimensions........ one under "details" @ 4.000" and one under "specs" @ 4.030" ...... so make sure that you speak to them while ordering.


Other than paying close attention to the deck height and compressed head gasket thickness, nothing else requires being changed from a standard over-haul.

Please note that you will not be able to use a F/T piston with the smaller Vortec cylinder head combustion chambers. If this was an earlier SBC w/ 76cc chambers, you would be able to while also gaining a Q/E.

As for an update, I have the motor disassembled in my garage. When I can get the time from work I will be taking the block and the heads to the machine shop for any required machine work they identify as needed. I have been tinkering with the crank and cam looking for part numbers. the cam i think is a 022944???
Who sells a respectable rebuild kit? I dont know if I trust ebay.
If this is a roller cam Marine SBC engine, the camshaft and cam followers are very likely re-usable.

And is there any where I can download a Electronic manual for this motor. I am a descent wrench turner but always like to cross my Ts and dot my Is.
Click to expand...

Rshaw450 said:
So i should buy a rebuild kit before dropping it off at the machine shop?
NO...... let them look it over before ordering pistons. A first over cylinder will be .030" larger.

Also, I would suggest that the machine shop check/re-size the connecting rods and install them into each piston. They will have the heating oven and the know-how.
Click to expand...
 
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Oversizing and new pistons will pretty much double what you will spend for a reconditioned block. Only rebuild if the block is good, just needs maybe a honing/line bore. Once you start down the path of oversize pistons, the prices escalate with fury.
I wonder if you've looked/asked around locally for good used? Are there any used boat part junk yards in your area? You may find a good low hour complete 350 for maybe $500 and be back in operation rather than waiting for EVER to get your stuff back from the machine shop and paying 2500 for basically a bare short block.
 
o2batsea said:
Oversizing and new pistons will pretty much double what you will spend for a reconditioned block.
Agreed........, the cylinder boring will most definitely add to the cost.
The piston and ring purchase will be the same whether standard (4.000") or first over (4.030").

Regarding a reconditioned block........ most rebuilders will use the GM full dished pistons. At best, this is a poor choice!


Only rebuild if the block is good, just needs maybe a honing/line bore. Once you start down the path of oversize pistons, the prices escalate with fury.
Yes, but to the tune of boring only.
If it must be bored....... then it must be bored.... correct?

On average, each cylinder bore will run about $28 +/- (i.e., $231 +/-).
Like said.... if it must be done..... it must be done!

I wonder if you've looked/asked around locally for good used? Are there any used boat part junk yards in your area? You may find a good low hour complete 350 for maybe $500 and be back in operation rather than waiting for EVER to get your stuff back from the machine shop and paying 2500 for basically a bare short block.
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Rshaw, I fully understand what o2batsea is suggesting.
However, you will not know whether the cylinder block makes the cut or not until the machine shop inspects it.

Let's not get the cart ahead of the horse just yet! :D


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I dunno, with all the metal shards and milk shake sludge in the pan, this doesn't sound good for the 'ol block.
 
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