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I need a new 5.7L block

S

Sutton1996

New member
I have a Sylvan 18' ski boat with an open bow. It is equipped with a chevy 5.7L engine with mercruiser components. I think I have a cracked block, and am ready to replace the motor. The casting # on the block is 10054727. I need to know if there are certain 350 blocks that will be an exacgt match so I can build a new motor for it. I intend to build a marine motor. SoI am really hoping to avoid a discussion about putting car motors into boats. As stated I have all other accessories like starter and water pump etc. so I really am looking for block info. Any help will be greatly appreciated.
 
The basic Mercruiser and Car Blocks are the same.

The Marine versions always used the heavy duty internal components.

Does your old block have a Steel Crank and 4 Bolt Mains?

Bruce.
 
I'll know for sure tomorrow. Im pulling the motor and will drop the pan to see exactly what happened. I'm fully expecting to find 4 bolt mains ans a steel crank.

I'm just wondering if I need a block from a certain range of years, or if a 350 4 bolt main is a 350 4 bolt main. I have an 84 suburban that I would like to upgrade from the 350 to a 454 sometime. I'm wondering if I should consider pulling that motor and using the block. Just want to make sure all the add ons will bolt right up.
 
MY advice, get the serial number and either post here or go to a marina and find out what exact type motor it is.

dont screw around with car or truck motors and try to make then marine ready.

do some reaserch in your area for a engine remanufaturer who does marine motors and get a replacement remanufactured short block or long block (typically around $1200-$2000) , swap all the neccesary parts be done with it and enjoy your summer.
 
what year boat motor ? You said 84' truck motor. But at this very moment with the info i have; if the boat motor is before 90' then all you have to do is install brass casting plugs, marine head and mani gaskets, and tranfer over your riser and other external marine parts your good to go, no need to change anything internal on the motor.

I am assuming your risers and mani's are good. But for 500 american dollars sometimes closer to 400 on some websites you can get a kit with 2 mani's 2 risers and all the gaskets delivered to you all in one box depends on the website and make of parts.

Oh yea glad we avoided the the discussion of truck versus marine motor cause there is no difference seeing as they are made bye gm on the same assembly line.
 
AGAIN why waiste time building a motor????????

A brand new GM truck long block is under $2500 dollars.

If you rebuild a motor you will need to buy a ton of parts, have machine work done, assemble it, test it and hope all is done right!!

If you buy one that all that work has allready been done to and just swap the parts that are not included you can be done in ONE DAY and be back on the water...........


I have been down this road many times and when someone needs major motor work I REPLACE not REPAIR!!!!!!

A complete motor swap can and should be able to be accomplished in a weekend.
to take another motor and have it all redone will take weeks.............

Down time cost a lot of money, let someone else worry about the engine block who does it day in and day out......

JUST SAYING!
 
If your boat is a 1996 then odds are you have a VORTEC, roller cam, one piece rear main seal 350 cu inch motor. Typical standard HP is ~ 260- 280.

If it is a efi it may be higher but is is more due to the efi not the motor.

Complete refurbished long block delivered to you should be under $2000.00

then swap oil pump, oil pan, intake manifold and carb/injectors, alt, water pump, etc etc etc. and you will ne done.

On my local craigslist there are a few people who sell complete refurbished long blocks for $1200-$1500
 
I appreciate all the replies. Kghost, I have time, in fact more time than money, so that is why I am willing to build my own motor. With all due respect, I have more faith in my work than most craigslisters that I've met. I know you're right, I'll get back on the water quicker. But I'm not in that big of a hurry. Avg water temp around here right now is 40! LOL

I'll grab the serial # today when I take the motor out. I was told by previous owner this was a replacement motor, so I cannot assume it is the same year as the boat. It would make life easy to be able to use my old intake TBI, etc, any just plug iin the wiring harness.
 
If you have the time then I would find a local reputable engine guy, someone who can assit in decisions on what would be the best parts combo's and see what you can do.

Again As I said that year boat would have had a one piece rear main seal motor, most likely a vortec, and roller cam. That is what a customers inboard 1996 had in it when I did a remanufactured motor exchange for him several years ago.

What is important is the flywheel mounting for the motor i believe. (could be wrong)

If that is not an issue than most any good 350 will work, no need for a 4 bolt main if not accessable. 2 bolt mains will work just fine if put together right.

Just do your reaserch and make sure you marinize the motor, freeze plugs, gaskets etc etc.

The oil pump should be reused or a new MARINE specific purchased. the oil pans and pumps are specific for marine motors and typically are a bit different than automotive. (shape and location of the pump pick up.) also I think marine pumps pick up tubes are brazed to the pump and screen, or should be anyways.........

good luck and let us know how much it costs in the end.

it will give us a good cost reference for the do it yourselfer vs buying a ready to go long/short block.
 
most 10054727's were 2 bolt mains according to the internets

nothing special about it - truck and car 350, 1 pc rear main seal

2 bolt main is what most marine 350's are
 
I'm fully expecting to find 4 bolt mains ans a steel crank.
Click to expand...

Ayuh,... I Doubt it...
A boat motor like your's is pretty much Exactly what Chevy was putting in pickups of the Same Vintage....

What year is the boat,..??
 
I to have more time than money, and prever to rebuild my ownh engines. At least that way, I know what I am putting into it, and what it will stand.

Wish we could buy Long Blocks down here for under $2,000.00.

A basic complete Re-build here costs me around $3,000.00 for a SBC.

Bruce.
 
Taz the junk yards here are full of them, you think all the motors that were supposed to be destroyed were ? There is a yard here where they have running 5.7's on pallets.

Just rows and rows of them, i asked the owner what he wants for them he said make me a offer, i bet he would take 200 bucks, and get this the milage of the cars they came out of are marked on each one he said that they are true milage he didn't want a pissed off customer, this guy is as honest as you can get in the buss.
 
Yeah, yeah, yeah, so I'm a dork. Of course it was a 2 bolt main. You guys knew that already.

So the boat is a 1998, and the motor had a date stamp on it of 08/05.

So back to original question. The 350 in my old mudder rig runs great. But I want a 454 in that before next winter anyway. SO..... why not use that block as a starting point for the new boat motor. Should I do a complete rebuild? Or leave the bottom end in tact, replacing the oil pump with the marine version and water pump, and throw in some Brass freeze plugs. I looks like all the add ons will bolt right up. Could even throw the vortec heads on the block from the blown motor, toss insome new cam bearings and a marine cam?? Motor is stock in a 1984 Chevy suburban. will my intake abd TBI bolt onto the setup?

Lots of questions. Guess I'm showing my ignorance. I have opinions on all these questions of course, but would like neutral opinions.
 
And why not just bolt up your mani and riser off the old motor on the truck motor drop it in and go. Oh yea check the casting plugs might need changing to brass if you boat in saltwater same with the gaskets marine.
 
If this wasn't a small 18 footer, I'd suggest steering clear of any truck engine. However, this is not as critical for this size hull......., minus the Marine Head Gaskets (if raw water cooled), brass casting plugs, etc.
If this was a cruiser, I'd say steer clear of any Dished Pistons when building one!

Here is your existing engine by casting number:
10054727... 350... 86-up... 2 or 4... one piece rear seal, some "Made in Canada"
So in order to stay with a "like" engine block, find a core block with this casting number!


Apparently, there is no Vortec association until:
10243878...305...96-98...2...Vortec truck, roller cam, one-piece rear seal
10243880...350...95-00...2 or 4...Vortec truck, Gen.I crate motors and "ZZ4", roller cam, one piece rear seal
 
Last edited:
Motor is stock in a 1984 Chevy
Click to expand...

Ayuh,... Your truck motor is a 2 pc. main seal motor...
It Won't swap as easily as another motor from 87 to present....
Btw,.. No such thing as a Marine oil pump... Just a Standard oil pump is used..

87concord,.... You've Hy-Jacked Sutton1996's thread,+ are creating nothing but CONFUSION....
Start your Own thread dude....
 
My experience is that a standard auto/truck oil pump is just that.

A marine, at least the ones I have had apart and seen had the tube welded/brazed to the pump and screen. Not the case with automotive typically.

Also the oil pans are not the same as automotive, Typically due to automotive/truck use specifically shaped pans based on frame configurations. Marine chevy (350) use the same. It may be a standard automotive type but it is specific for a marine engine and is always the same.

There were some different big block pans used over the years ( 4-5 qrt vs 7 qrt)

Therefore the oil pump is specific to the pan.

I hope I explained my opinion correctly.
 
A marine, at least the ones I have had apart and seen had the tube welded/brazed to the pump and screen. Not the case with automotive typically.
Click to expand...

Ayuh,... But the pump is still the Same pump...
The tube,+ screen are welded by the Installers....
Hot Rodders do the Same thing All the time....
 
Thanks for the input guys. I found a nice used block from a 1990 Suburban. 2 bolt, one piece rear main. I cannot spot any differences in the blocks whatsoever. I will take your advice and make sure to use Brass freeze plugs, and I'll grab the water pump off of the lost motor. (It was a very new motor, operator error caused the failure). I will also be sure to use marine gaskets. I will have new cam bearings installed and use the cam from old motor, since as I understand, they are a bit different for marine applications. I will also probably swap out the oil pump along with the pickup tube/screen assembly in order to avoid any possible issues. I should be able to use my pan as well.

Sound like a plan?

BTW, I acknowledge that you guys undoubtedly know more about this than I do. And the motors you guys build for customers are set to a higher standard. For me, it's kinda fun, and I have to stay on a budget. If I need to do it again in 5 years, no problem. I'll have goten my $'s worth.
 
Dont waste your time on cam bearings unless the donor motor is high milage.

Brass freeze plugs, marine head gaskets, marine water pump. Cam from old into new and possible a new timing chain!!!

Good luck,

Bondo

again my experience is the marine pump assemblies I have purchased had the pump tubes brazed....... not done by the motor builder.
 
Well I am in to this project for $620 right now. I bought a Block out of a 95 suburban, paid $225 for it. It had no cam, lifters, heads, I will use those from the old motor, as there was nothing wrong with them. I am in gaskets, seals, freeze plugs, timing set, and Hi temp silicone $360. These were all marine grade parts. next step in assembly is installing heads. I am getting a little short on time, so it might take a bit, but I will post final results and costs as I get closer to completion.

Thanks again for all the positive input!
 
Well the motor is in the boat and it is running. Seems to run fine. I need to put a timing light on it and finish bolting up a few ancillary items. Then reinstall seats and upholstery and stuff.

Total project costs are as follows

replacement block 225
Upper and lower Marine casket sets along with all ne brass freeze plugs 365

High temp RTV silicone 15

2 sets of oilchange supplies and power steering fluid 35

So it looks like 640 bucks. But I think I got a deal on the block.

Anyway thanks again for the tips.

BTW sounds like 4 degree advance is standard, is that where I should be, or should I just time it by ear and feel?
 
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