Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

[canadianguide]

Hi. We've got a 1985 Baja Islander 180 boat with a 4.3L OMC Cobra sterndrive. The engine blew last summer (cracked head and block...don't ask )<br /><br />Anyway, will any 4.3L bolt in? Specifically, I've got a 91 4.3L. Will it swap in? I think I will put the carb on it as the 91 is an EFI, but what concerns me most is the mating in the bell housing with the leg and the engine mounts. The exhaust, intakes and plumbing will be salvageable from my blown engine I believe. <br /><br />Will this work?<br />Thanks alot for your help.

 

[Bondo]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

what concerns me most is the mating in the bell housing with the leg and the engine mounts.

It Should be All the Same.......

 

[Trent]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

It is a marine engine your going to install? And not an engine straight out of a car?

 

[canadianguide]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

NO this engine came out of a 91 S-10 pickup. Does it make a difference?

 

[ZmOz]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

You can only use the long block of an automotove engine, and you will need to change the cam. The starter, carb, distributor, water pump, and alternator all need to be marine.

 

[canadianguide]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

Why do I need to change the cam? <br /><br />The starter, carb, distributor, water pump, and alternator can all be salvaged off my blown engine I believe. <br /><br />Any more information like this is most welcome. I haven't been able to find a clear answer as to how a marine engine differs from a truck engine. <br /><br />Thanks very much! Any more info is greatly appreciated!

 

[vinney]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

Bolt pattern on the crankshaft. Two piece rear main seal and new style one piece rear main seal. Engine coupler is different.

 

[dmorley]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

Candianguy,<br />Look at the discussion on this forum titled "Hey Vinney - reversition". The first few post deal with the satic line issue, but later post explain why you need a marine cam.

 

[Trent]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

Marine is different....Look here... web page

 

[ZmOz]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

You need a different cam because marine engines operate at different RPMs than an automotive engine. They spend alot more time at WOT. You should be able to use your old cam too...

 

[canadianguide]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

Hmmm...there is alot more different than I expected. Please help me make a list of what parts I need to change to make this automotive engine work?:<br /><br />I need:<br />Starter<br />Distributor<br />Water Pump<br />Carb<br />Alternator<br />Cam<br /><br />Is that it? These are all pieces I should be able to get off my blown engine, and in fact a few of them I already knew about, but more are a total surprise. <br /><br />THanks alot for your help..If you could add to this list I would really appreciate the help to make this work.

 

[John Carpenter]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

You will also need the marine fuel pump off the old engine. Check to see that the flywheel diameters are the same as well as the bolt pattern on the flywheel where it has to bolt up to the drive adapter. OMC changed adapters over the years.<br /><br />Check the location of the dipstick...right or left side? Also one or two piece rear main seal. GM made several changes to the small block in 1986. The link that Trent posted may have a lot of this info...didn't check. Good luck with the swap.

 

[akriverrat]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

raw water cooled=brass freeze plugs.

 

[Trent]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

Marine gasket set. (Stainless Steel head gasket)

 

[canadianguide]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

Originally posted by vinney:<br />Bolt pattern on the crankshaft. Two piece rear main seal and new style one piece rear main seal. Engine coupler is different.

So are you saying that this engine won't work? I don't understand this statement.

 

[TwoBallScrewBall]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

Since the 4.3 came out of a s-10 it will bolt up to the bellhousing just fine. However, what they mean about the coupler is this:<br /><br />Up till about 1988 GM used a 2-piece rear main crank seal. In about 1989 they switched over to a 1-piece seal, which also changed the design of the end of the crankshaft and the bolt pattern. The bolt circle on the newer engine is smaller. You will need to find a coupler off a 1990 or newer 4.3 and install that one on the new engine. Check Ebay, that's where I found mine when I switched from a 1988 to a 2002 3.0L in my boat. $40. New they're about $250. <br /><br />The S-10 cam will actually work pretty well in the boat, you could probably get away with using it. Definitely without a doubt swap out the starter, alternator, distributor and carb from the old engine... and the water pump if the engine is raw water cooled. Probably a good idea to do the water pump either way.<br /><br />Good luck!

 

[canadianguide]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

but my new engine is a 91...why do I need to buy the coupler?<br /> <br />bear with me here...kinda learning as I go..thanks

 

[John Carpenter]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

I understand that you already have an engine...but from my experience, the best, easiest and cheapest thing to do is to use the correct year range block. If you insist on using the engine you have (and I can understand that) then you are probably going to have issues with sheet metal components. You have to know if they are both 1 piece or 2 piece rear main seals...the oil pans are different...dipstick may be on the wrong side. Look at your engines. Harmonic balancer may also be different.<br /><br />I think that the flywheel bolt patterns are different on the two engines you have. This means that your OMC drive coupling may not bolt up. It is easy enough to check...if the flywheels are the same diameter then the bolt pattern will be the same. Just measure them.

 

[canadianguide]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

Ok..so lets assume that my coupler is smaller on the new engine than the one on the blown engine. How can I remedy this? Can I swap flywheels??<br /><br />Also, what difference does it make where the dipstick is or whether the oil pans are different?<br /><br />Thanks for the help..this is great!

 

[John Carpenter]

Re: Newbie: Swapping a blown engine ( 1985 4.3L) Compatible?

I don't know if you can exchange the flywheels or not. My apologies for the comments on the sheet metal components...it doesn't matter if you have a complete set for both engines.<br /><br />If you use the marine components from the old engine, then your biggest concern will be the drive adapter. The OMC I did was a 1971 and the post 1986 flywheel pattern would not work with it. Yours may be fine...I don't know the years that OMC made changes to the adapter.