1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

lambert34 · Mar 18, 2013

Is it even possible for me to do this? I picked the cobra up today assuming it would be compatible and running into issues with the coupler and flywheel. Can i pick up a coupler off of a 3.8 and make it work? Both housings line up perfect, there just isnt enough room with how big the coupler is thats on the 4.3. Please help.!!!!!!!!! If there are other things that need to be changed please list as well. Im a new boat owner and dont know much about this, so all the help i can get would be much appreciated. Thanks

Howard Sterndrive · Mar 18, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

lambert34 said:
Can i pick up a coupler off of a 3.8 and make it work?

when you say you are converting from a 3.8, where did the coupler go off your 3.8?

If you mean that your 3.8 coupler won't fit on the 4.3 because the crank flange bolt pattern is different then yeah, if your 4.3 is newer than 1986 that will certainly be the case.
If the 4.3 is 1987 to 1998, then you cannot couple it to a 1984 800 series drive.

You need another 3.8 (Chev 229), or the rare one year 1985 to 1986 4.3 with the old style crank. Any V6 engine newer than that won't work with the 84 sterndrive.

lambert34 · Mar 18, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

Well my wife thought she would be nice and buy me a boat for xmas. She decided to suprise me with the 84 sea sprite with no motor that she thought she got a deal on craigslist. Very thoughtful but extremely frustrating. So no coupler from old motor. Not sure what year the cobra is. I know it came out of a 1989 Ciaition. Anyway.....The bolt pattern on the flange is the same. I just didnt know if there was a coupler out there that was small enough to fit behind the flywheel so the housing will bolt together. Do i need a different flywheel as well?

lambert34 · Mar 18, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

Or will this even work at all? Please have good news for me before i start shopping

Nivekt · Mar 19, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

Im a little confused as to what you have exactly. How about posting some pictures?

Bondo · Mar 19, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

lambert34 said:
Well my wife thought she would be nice and buy me a boat for xmas. She decided to suprise me with the 84 sea sprite with no motor that she thought she got a deal on craigslist. Very thoughtful but extremely frustrating. So no coupler from old motor. Not sure what year the cobra is. I know it came out of a 1989 Ciaition. Anyway.....The bolt pattern on the flange is the same. I just didnt know if there was a coupler out there that was small enough to fit behind the flywheel so the housing will bolt together. Do i need a different flywheel as well?

Ayuh,.... Welcome Aboard,.... That woulda been a Stringer drive,...

Donno why you'd wanta refit a Cobra....

jerryjerry05 · Mar 19, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

Like Bondo says. The 84 is a completly different setup
Pics of the old and new??

lambert34 · Mar 19, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

It doesn't bolt together because of how big the coupling is on the cobra engine. I was wondering if I could use a smaller coupler. Like the ones that are used in the 3.8. I'll try and get pics up later on.

lambert34 · Mar 19, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

To Nivekt. I have a 1984 Sea Sprite Contender III. Came without a motor. It has a v6 Stern Drive out drive. Im trying to put a 4.3 liter cobra in it. Having trouble coupling them together.

Don S · Mar 19, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

lambert34 said:
To Nivekt. I have a 1984 Sea Sprite Contender III. Came without a motor. It has a v6 Stern Drive out drive. Im trying to put a 4.3 liter cobra in it. Having trouble coupling them together.

Now it makes more sense, I thought you was trying to put a Cobra outdrive, onto your 3.8 engine.

What you really want is to replace the 3.8 engine with a 4.3 engine.

FYI Cobra is an outdrive, not an engine.

southkogs · Mar 19, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

Welcome aboard Lambert:

What everyone's concerned more about (at just this moment) is that your boat - by it's year - should be rigged for an OMC Stringer Sterndrive, and you're trying to mount an OMC Cobra Sterndrive: The OMC Stringer has a MUCH larger hole in the back of your boat meaning the OMC Cobra CAN'T install to your boat without you completely rebuilding your transom. Doesn't matter if it'll couple to the engine or not ... it can't sit on the boat.

Several other questions abound, such as "why would you go to all of this trouble to go to a Cobra, when you could (with the same effort) get a more supported drive system for roughly the same investment. You're kinda' trying to jump outta' the fire into the frying pan - from what we can tell.

ezmobee · Mar 19, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

Your wife bought you a motorless boat with a Stringer setup for xmas? That's like the worse xmas gift ever.

Bondo · Mar 19, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

ezmobee said:
Your wife bought you a motorless boat with a Stringer setup for xmas? That's like the worse xmas gift ever.

Ayuh,.... it Does make a chunk of coal mighty prutty...

'n I believe the Stringer uses a flex-plate, not a rubber coupler...

Howard Sterndrive · Mar 19, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

lambert34 said:
It doesn't bolt together because of how big the coupling is on the cobra engine. I was wondering if I could use a smaller coupler. Like the ones that are used in the 3.8. I'll try and get pics up later on.

If your motor is an 89 then NO. You bought a motor that cannot be mated to the 1984 drive.
You can buy the smaller, old style solid 3.8 coupler but it won't bolt up to the back of the crankshaft of that 4.3, sorry.

There is NO coupler that will connect that engine to an 84 drive.
Sell the 89 4.3 and get a 1981-1984 3.8 (Painted Blue) or a 1985-86 4.3 (Painted silver) so you can use the old style solid coupler.

Howard Sterndrive said:
You need another 3.8 (Chev 229), or the rare one year 1985 to 1986 4.3 with the old style crank. Any V6 engine newer than that won't work with the 84 sterndrive.

lambert34 · Mar 19, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

Thanks Howard. Well I suppose I'm going to try and resell this motor. It is a really clean motor too. Runs and sounds great. I just wish I would have done a little research before I ran out and bought it. If anyone is interested send me a message. Thanks again for all the help everyone.

ezmobee · Mar 19, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

You should sell EVERYTHING and start over.

lambert34 · Mar 19, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

I'm starting to think the same thing

ezmobee · Mar 19, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

lambert34 said:
I'm starting to think the same thing

The two biggest pitfalls of a used boat are rot in the wooden components of the hulls (deck, stringers, transom) and an obsolete powerplant. You want something with a Mercruiser or Volvo powertrain with a Chevy based block. Also check carefully for rot. ANY soft spots in the deck are usually indicative of more serious trouble below in the stringers. Generally, if the boat has a pretty rough looking interior, chances are good it's spent some time uncovered out in the elements and rot could certainly be present. Unfortunately, a nice looking interior does not guarantee there isn't rot. If you want to get on the water cheaply with the least chance of financial disaster, I recommend an aluminum hull.

jerryjerry05 · Mar 20, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

Were you located? Profile? Location?
You might be close to someone who can help??

lambert34 · Mar 20, 2013

Re: 1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

Ohio

1984 sea sprite 3.8 liter conversion to 4.3 liter cobra??????????????

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