Need a list of compatible 4.3 engine to OMC Cobra 4.3

[houstonnoob]

Hi I have 88 Sunbird with OMC Cobra 4.3l that I have own for in the last 36 hours. This is my first boat, I bought the boat with "engine problem" as a project but I didn't expect to see the golfball size hole in the #1 cylinder. Now I will need a used short block or the entire engine depending on the $. It appears trying to obtain the exact engine OMC cobra 4.3 nearly impossible to find or they want an arm and a leg for it.

I've seen counless short or long block of 4.3L for reasonable cost however it is not OMC Cobra 4.3. I would like to do a straight swap. Is there any 4.3L V6 motor out there I can swap with my OMC Cobra 4.3? Help.

Thank you.

 

[horndog]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

It is is based off of the GM 4.3L engine, so the mercruiser and OMCs are virtually the same block.

 

[bbgun24]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

I went through this last year. I went to a local junkyard and picked up a 1992 4.3L out of a chevy 1500. One thing you want to make sure of is that the block has a hole for the mechanical fuel pump. I think in 1992 GM switched over to an electric fuel pump.

 

[houstonnoob]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

It is is based off of the GM 4.3L engine, so the mercruiser and OMCs are virtually the same block.

I went through this last year. I went to a local junkyard and picked up a 1992 4.3L out of a chevy 1500. One thing you want to make sure of is that the block has a hole for the mechanical fuel pump. I think in 1992 GM switched over to an electric fuel pump.

Thank you for your info. So basically I will need a pre 1992 chevy 4.3L engine with a mechanical fuel pump? What about all other attachments such as OMC exhaust manifolds, bell housing, engine mount, etc. Do I require to do any modification on the engine? I need a straight forward swap by reattaching the original components from my old cracked OMC Cobra 4.3L to the pre 1992 chevy 4.3L long block. I can get my hand on the chevy 4.3L from the junkyard for about $200. If this really work, it'll save me bunch of time and the money. At one point I was about to give up because the engine cost like 5 time the amount I've paid for the boat.

 

[Bondo]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

Thank you for your info. So basically I will need a pre 1992 chevy 4.3L engine with a mechanical fuel pump? What about all other attachments such as OMC exhaust manifolds, bell housing, engine mount, etc. Do I require to do any modification on the engine? I need a straight forward swap by reattaching the original components from my old cracked OMC Cobra 4.3L to the pre 1992 chevy 4.3L long block. I can get my hand on the chevy 4.3L from the junkyard for about $200. If this really work, it'll save me bunch of time and the money. At one point I was about to give up because the engine cost like 5 time the amount I've paid for the boat.

Ayuh,.... '86, 'n earlier will be a 2 pc. rear main seal, so, ya need an '87 to '90-ish replacement to bolt all yer OMC stuff too....

A later motor is adaptable, like with an electric fuel pump, properly wired in...

 

[houstonnoob]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

Ayuh,.... '86, 'n earlier will be a 2 pc. rear main seal, so, ya need an '87 to '90-ish replacement to bolt all yer OMC stuff too....

A later motor is adaptable, like with an electric fuel pump, properly wired in...

Mr. Bond,

Thank you for your input, now I've narrow down to GM 87-90 4.3L motor from junkyard, which is easy and cheap to get my hands on that don't require me to give up my arm and a leg. I know you have stated "'87 to '90-ish replacement to bolt all yer OMC stuff too...."
I'm concern about the flywheel and the mating of the bell housing. And also I've searching and reading the threads here, some peoples say the cam will need to be swap from my old OMC to the GM block. I've told the marine engine rev higher because it always on WOT, if not swapping the cam does it make the engine less reliable in long or short term? I prefer not to open the GM long block engine at all if it's not a major issue.

 

[Bondo]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

Mr. Bond,

Thank you for your input, now I've narrow down to GM 87-90 4.3L motor from junkyard, which is easy and cheap to get my hands on that don't require me to give up my arm and a leg. I know you have stated "'87 to '90-ish replacement to bolt all yer OMC stuff too...."
I'm concern about the flywheel and the mating of the bell housing. And also I've searching and reading the threads here, some peoples say the cam will need to be swap from my old OMC to the GM block. I've told the marine engine rev higher because it always on WOT, if not swapping the cam does it make the engine less reliable in long or short term? I prefer not to open the GM long block engine at all if it's not a major issue.

Ayuh,.... The flywheel/ bellhousin' issue is 'tween the 2 pc rear main seal, 'n the 1 piece....

If ya find a pickup truck motor, I wouldn't worry 'bout the cam,...
When folks talk 'bout a car/ truck cam bein' incompatible, it's the Hod-Rod cams are the Problem,...
Not so much the stock cams...

If ya can find a boneyard motor that runs, with decent compression,...
I'd bolt yer OMC goodies onto it, 'n go Boatin'....


Btw,.... Mr. Bond was my Dad,.... I'm just Bondo...

 

[houstonnoob]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

Ayuh,.... The flywheel/ bellhousin' issue is 'tween the 2 pc rear main seal, 'n the 1 piece....

If ya find a pickup truck motor, I wouldn't worry 'bout the cam,...
When folks talk 'bout a car/ truck cam bein' incompatible, it's the Hod-Rod cams are the Problem,...
Not so much the stock cams...

If ya can find a boneyard motor that runs, with decent compression,...
I'd bolt yer OMC goodies onto it, 'n go Boatin'....


Btw,.... Mr. Bond was my Dad,.... I'm just Bondo...

Bondo, James Bondo:

Thank you again. Very positive feedback and suggestions. Now I am ready to remove the blown engine from the boat. Since I am on my 48 hours since I've own my first boat and I do not have the repair manual, can you please give me some tips and procedure?

Can I remove the motor with the entire thing that hang out on the back that has the propeller still attached to the end of the boat? I don't know what they call it, I read peoples say Transom, outdrive, lower unit, stern drive, or something like that, but I don't know which is which. I've NEVER work on the boat before, please help me.

Anyone and anybody please provide me with some guiden. Thanks

 

[wcasey5]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

here is the manual

http://www.mediafire.com/?j74z0nib459gh

 

[houstonnoob]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

here is the manual

http://www.mediafire.com/?j74z0nib459gh

Nice, thank you very much for the manual.

 

[houstonnoob]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

OK I've spent few hours reading through the repair manual. Please correct me if I am wrong. So base on the manual I can leave the "vertical drive", I am assuming the entire section on the back outside of the boat attached while removing the engine. After disconnecting manifolds, hoses, and wires, all I have to do is lift the engine up slightly and pull the engine forward and it will detach the engine and U joint shaft with splines thing. Am I understand this correctly?

 

[Kainon]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

you can leave the outdrive attached ONLY if you have sufficient room to slide the engine forward and up about 4-6 inches off the input shaft you can tilt up a bit, but going on could be more tricky depending on how much room you have you'll have to decide. taking off the outdrive is easy, put in forward, remove 6 nuts and pull. ( dont want to use a pry or screw driver if possible )

dont use the auto starter, altenator, ignition, nor water pump.

If the engine you get has steel freeze/block plugs you may want to consider changing to Brass, just a thought.

 

[Bondo]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

After disconnecting manifolds, hoses, and wires, all I have to do is lift the engine up slightly and pull the engine forward and it will detach the engine and U joint shaft with splines thing.

Ayuh,.... You Can do that,.... But,....

The drive has to come off, anyways, to reinstall the motor, 'n Align it....

 

[wcasey5]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

I just took my drive off, it took all of 20 minutes. And I had never did it before.

 

[houstonnoob]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

you can leave the outdrive attached ONLY if you have sufficient room to slide the engine forward and up about 4-6 inches off the input shaft you can tilt up a bit, but going on could be more tricky depending on how much room you have you'll have to decide. taking off the outdrive is easy, put in forward, remove 6 nuts and pull. ( dont want to use a pry or screw driver if possible )

dont use the auto starter, altenator, ignition, nor water pump.

If the engine you get has steel freeze/block plugs you may want to consider changing to Brass, just a thought.

There's about a dozen of freeze / core plugs on the engine front, back, side, do I need to replace them all?

What do you mean put it in forward? I've disconnected most of the power/cable, not sure if I can put in forward. The vertical drive is in tilt position. The engine has been removed from the boat and on the engine stand now.

Ayuh,.... You Can do that,.... But,....

The drive has to come off, anyways, to reinstall the motor, 'n Align it....

You're correct it can be done however it does look hard to insert the drive shaft into the end of the engine, i don't know what everyone call it. I will attempt to remove it, but is there any gasket or seal I need to replace if I remove the vertical drive?

I just took my drive off, it took all of 20 minutes. And I had never did it before.

How much does the vertical drive weight? Do I need to have engine lift or something? I've read about how to build your own vertical drive stand, this I can do. But wonder if it's too heavy for one person.

 

[Bondo]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

I will attempt to remove it, but is there any gasket or seal I need to replace if I remove the vertical drive?

Ayuh,... It's Got to come off,.. no doubt 'bout it....

There's usually a seal/ gasket set available...
You'll need an Alignment Tool as well,...

How much does the vertical drive weight?

'bout 80/ 85lb.s...

 

[wcasey5]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

it weighs less than 100 lbs. I got my son to help me with it just to get it off the back of the boat. But I can move it around by myself. No crane required.

 

[houstonnoob]

Re: Need a list of compatible 4.3 engine to OMC Cobra 4.3

Ayuh,... It's Got to come off,.. no doubt 'bout it....

There's usually a seal/ gasket set available...
You'll need an Alignment Tool as well,...


'bout 80/ 85lb.s...

I have no clue on what type of sterndrives or what ever is call it, all I know is I have a OMC Cobra 4.3L. Will this alignment tool workfor my engine?
http://www.ebay.com/itm/BRAVO-ALPHA..._Accessories_Gear&hash=item3f172dfb13&vxp=mtr

Should I replace the entire freeze/core plugs on front, sides, and back of the block? I've read some people hammer the plugs back on with and without some sort of rtv gasket maker. I'm not so sure why rtv gasket maker thought. What is the correct way, with sealant or without?

it weighs less than 100 lbs. I got my son to help me with it just to get it off the back of the boat. But I can move it around by myself. No crane required.

Thank you for your input.