4.3L OMC engine swap time

J

jpwdesigns

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I've got to swap out engines. Cracked block. 1986 Starcraft 4.3L Cobra outdrive.

I'm evaluating the following:

  1. Reman Long block from Rapido. Would have to look at also getting new exhaust mani's. Probably cost $2500+
  2. This ebay engine http://cgi.ebay.com/ebaymotors/ws/e...ewitem=&sspagename=STRK:MEWAX:IT#ht_500wt_698
  3. Getting a salvage shortblock and putting old heads, intake manifold etc.. on. Cost $400 give or take for the short block?.

Thoughts?
 
Idlespeedonly

Idlespeedonly

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Re: 4.3L OMC engine swap time

If you can get the ebay motor for a decent price, you could have it installed in as little as an hour. Then on your way to the lake. As for using your old heads I wouldnt do it without having them checked out.
 
Joshua Nichols

Joshua Nichols

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Re: 4.3L OMC engine swap time

The ebay engine could be a winner.. Could be a loser..
Anything that isn't cracked you can reuse.. If you want.. Exhaust manifolds would be a good thing to replace.. I have a set of OSCO manifolds I replaced mine with and they are pretty good American made stuff

BTW that downloadable manual sucks, but if that's all you got.. That's all you got.. I would buy a factory if I was you and planning on keeping the boat...
 
J

jpwdesigns

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Re: 4.3L OMC engine swap time

Joshua Nichols said:
BTW that downloadable manual sucks, but if that's all you got.. That's all you got.. I would buy a factory if I was you and planning on keeping the boat...
Click to expand...

HI I found this and I'm trying to figure out if it is the right one for my engine. I'm a little confused about which engine I have because i think there were some changes between 86 and 87. I think my boat was manufactured in 86 but shouldn't i be able to tell some how for sure? http://cgi.ebay.com/ebaymotors/OMC-..._Literature&hash=item2eb3a5ff27#ht_5545wt_939
 
Bondo

Bondo

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Re: 4.3L OMC engine swap time

jpwdesigns said:
That engine is running 155, 155, 150, 155, 150 AND 155 compression.....my crap manual says it should be 160-170. Little low, is that a red flag?
Click to expand...

Naw,... 150/ 155 is fine...
 
Joshua Nichols

Joshua Nichols

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Re: 4.3L OMC engine swap time

Mine is 155 and screams

Don't get your hopes up... Those engines go for 2K on ebay all the time... That is drop in power... Change your 4 barrel intake... whoot whoot... Most of those sales have a video of it running... Funning thing.. As you know they will run fine with a cracked block.. Even on a hose
 
J

jpwdesigns

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Re: 4.3L OMC engine swap time

Wife informed me last night that working on a boat engine at 12:30 am is out of control :p

Pulled exhaust manifolds, distributor, carburetor, intake manifold, etc....Big *** crack in the block of course as already diagnosed. Creamy milkshake everywhere. What a mess.

Any recommendations on how to clean parts coated in this stuff? kerosene, brake cleaner?

Also, I may try to save the heads to use on a salvage auto engine short block. Thoughts on that?
 
Lou C

Lou C

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Re: 4.3L OMC engine swap time

brake cleaner but use the non chlorinated kind, safer...
heads, well since the block was cracked, they could be cracked too, can you take em to a machine shop and have em checked?
You know I have wondered about this engine re-man stuff, I read all the time on here and other sites about Rapido and Michigan Motorz, but when the time comes for me, I want to find a local place,that can get me a new GM crate 4.3, if they are still available when the time comes. I'd go rent a trailer for a day, pick it up (cheaper than shipping) and I want some semblence of local service, a real guy to talk to. Ive bought a lot of stuff internet/mail order all my seating, manifolds, etc, but a motor, there's so much that could go wrong....yes the crate motor costs more but it's NEW....put closed cooling on it and that's gonna last you for ever....

I gotta give you credit for sticking with this, these are the things that happens with older used boats, you will be a pretty good marine back yard mechanic by the time you get done.
First....best thing you can do....try to get an OE OMC shop manual, I have one that I bought when you could still get them from BRP dealers...
Then....look at this from a different viewpoint, you have a nice boat, you will have to put money in, but if you went and bought a new 20' bowrider, in 3 years you would lose between 10 and 15 grand on depreciation. No way around it. I plan on repowering my old FW when the time comes, and I am keeping the Cobra system as long as I can get parts. It works great, no need to convert now. Plenty of OE, used and aftermarket parts around, just bought a pair of excellent condition trim cylinders, to stow away in the garage.

My boat has original mechanicals, but the deck and interior had to be replaced, even with me doing at least half of it, that cost as much as a ccrate motor! But the boat looks new inside and is very solid, great running hull.

So my advice, is check out LOCAL engine sellers/rebuilders first, if you have local marinas, find out who they use...could save you trouble in the long run....
 
J

jpwdesigns

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Re: 4.3L OMC engine swap time

Lou C said:
brake cleaner but use the non chlorinated kind, safer...
Click to expand...
Thanks Lou

Lou C said:
heads, well since the block was cracked, they could be cracked too, can you take em to a machine shop and have em checked?
Click to expand...
Will do. What should I expect to pay to have them checked out?

Lou C said:
I gotta give you credit for sticking with this, these are the things that happens with older used boats, you will be a pretty good marine back yard mechanic by the time you get done.
Click to expand...
Thanks again.

Lou C said:
First....best thing you can do....try to get an OE OMC shop manual, I have one that I bought when you could still get them from BRP dealers...
Click to expand...
On its way from ebay ;)

I'm thinking of rebuilding the engine myself. I just having a hard time getting my head around spending as much as I paid for the boat for a new engine. not to mention i'm not made of money and my other half will probably freak if i drop another 1500 on this thing. I enjoy learning and working on this stuff...always worked on my own motorcycles and can read a manual. So I'm currently researching getting a salvaged block with same casting number and putting my gutz in it. Am I stupid for thinking this? Anyone else tried it successfully?

Found this core http://pegtiming.com/Timing/Advance...=4&SKUTYPE=202&SKUFLD=SKU&DM=1250&WEBID=21868

Block# 14088553 one piece rear main seal with open fuel pump hole
Heads# 14079248
 
Joshua Nichols

Joshua Nichols

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Re: 4.3L OMC engine swap time

You can build one...

Did a bit of research on this once.. It's almost as cheap and certainly easier to buy one from Rapidio, than it is to buy a core block and build a engine..

You can take a 4.3 from a ol wreaked pick up.. Change out the core plugs to brass.. Change the head gaskets and use it.. That would have to be the cheapest way... I see them all the time going for 600 bucks all the time.. Swap all that stuff.. Put you gear on it and you will be in that water by mid fall easy...
 
M

mrv8outboard

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Re: 4.3L OMC engine swap time

GLM make a kit to convert the OMC exhaust to MERC style center risers. As wel as SEI has a kit that will let you bolt an Alpha drive to the OMC transom assembly. There is a shift assist module for these. They are specific to points type or Prestolite electronic (not after market electronic) so make sure not to mix them up.
 
Lou C

Lou C

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Re: 4.3L OMC engine swap time

I've thought of doing it myself, and I've been wrenching on my own vehicles, lets' see, since Nixon was president (1972), but I think one needs both special skills and tools that most people would have to rent, thereby driving up the cost. I vote for the GM crate engine, new, you can run that boat for years as long as you want, instead of chasing problems. Trouble free operation, esp in a boat, is worth some money to me. Now if I had access to a machine shop, had the time and someone to guide me through it...maybe....but none of those circumstances exist in the present....
 
J

jpwdesigns

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Re: 4.3L OMC engine swap time

iphone 007.JPG
Ok, I think I've found my replacement engine. A well running complete engine. 1986 from a truck with 100k miles, 6 month warranty.

SO, what I think i'm going to do is leave the cam alone and just swap heads and tin. Debating what to do about the old exhaust risers. After getting them off and inspecting one was welded. Not JB Weld but real weld.

I'll have to replace these gaskets:

- heads
- intake manifold
- exhaust manifold
- water pump
- thermostat housing

Am I missing anything?..I'm trying to take stock of all the necessary bits and bobs before starting.

Are there any gaskets that I could safely use permatex gasket maker instead on? Asking cause some of these things are expensive.

Last question for this post...What about the brass drain plugs on the bottom of my engine, are there holes on auto blocks for these?
 

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Bondo

Bondo

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Re: 4.3L OMC engine swap time

I'll have to replace these gaskets:

- heads
- intake manifold
- exhaust manifold
- water pump
- thermostat housing
Click to expand...

Ayuh,... The Heads are fine as they are,...
For the brass drain fittings, Yes, the drillings are there......
'n use Gaskets wherever necessary,... Good 1s,... like Fel-pro...
 
bruceb58

bruceb58

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Re: 4.3L OMC engine swap time

You need to replace the freeze plugs(casting plugs) with brass ones.
 
J

jpwdesigns

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Re: 4.3L OMC engine swap time

Bond-o said:
Ayuh,... The Heads are fine as they are,...
For the brass drain fittings, Yes, the drillings are there......
'n use Gaskets wherever necessary,... Good 1s,... like Fel-pro...
Click to expand...

Thanks Bond-o. Are you saying I don't need to change the heads on the truck engine to heads off my marine engine? Or that I don't need to change the gaskets when swapping heads?

If I don't need to swap heads that would be great. Save me time and money on gaskets. It would also mean i'm definitely leaving the cam alone.
 
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