84 V4 90 hp Evinrude swap?

[CichlidMan]

Hello, this is my first post here, and i dont know much about boat motors, im actually helping my dad. But anyway here goes.

We have a 73 85 hp Evinrude 4 stroke engine that blew a piston, after seing how much work and money it would take to fix, we decided to start shopping for a new motor, we ended up buying a 84 90hp v4 evinrude motor. We did not have all the parts required to the oil injection system and from searching they can start to add up.
So in a nut shell i was wondering what would all be interchangeable from the 2 motors. My dad already swithced the carbs, choke system, and fuel pump.

Will this work or is he waisting his time?
Any help would be appreciated!!!! ty

 

[ezeke]

Re: 84 V4 90 hp Evinrude swap?

The carburetors will work, but I personally think you are taking a great step backwards. The 1984 carburetor system is much improved over the earlier mecahnical choke system. Besides that, it could very well have been the carburetors that caused the loss of your piston.

The fuel pump on the 1973 motor can be adapted to run the 1984 motor, you just need a place to mount it.

Just about everything below the powerhead and in the powerhead is different on the the 1984 motor and can't be swapped. Also, items such as the flywheels look the same but will not work if switched. The engine blocks including the crank are different.

 

[Dhadley]

Re: 84 V4 90 hp Evinrude swap?

Agreed, if what you had was a 1973 85hp 2 stroke (we'll assume it was since there was no 1973 85hp 4 stroke) putting those carbs on the 84 90 is definately going backwards.

If you bought the 84 90hp as a running motor all you need for oil injection is the tank, provided the pump is on the motor. If it's a running motor it has to have some sort of fuel pump.

 

[Dhadley]

Re: 84 V4 90 hp Evinrude swap?

BTW - if you're trying to put the 84 powerhead on the 73 mid, it will work but you have to change 4 of the mounting bolt locations on the base of the 84 block.

 

[CichlidMan]

Re: 84 V4 90 hp Evinrude swap?

Thank you for the quik response, we are trying to get back on the water before the winter. Well, i decided to dig a little more myself and googled the model # of the older motor, and it is a 78 85 hp evinrude. Does this change the situation at all ?

So if we switched back to the origional parts on the 84, assuming the fuel pump works, how do we go about bypassing the oil injection system and just mix fuel manually 50:1 ?

 

[ezeke]

Re: 84 V4 90 hp Evinrude swap?

You can block the oil line on the VRO systems and use pre-mixed fuel, or, you can bolt the 78 fuel pump (PN 388268) directly to the intake manifold.

 

[CichlidMan]

Re: 84 V4 90 hp Evinrude swap?

Alright so, i talked him into swtiching all the parts back, put the carbs back on, kept the 78 fuel pump on, motor runs good with new plugs in. Has great power when giving throttle, but wont idle? After a few minutes of running, pull the plugs out and everytime plug 1 & 4 get fowl up with black carbon? I tried this a couple of time and its the same, 1 & 4 keep going black, plug 2 & 3 run like there suppose too. Any suggestions?
Also, the timing was off due too the clip that holds the flyweel broke and flyweel spun around. Could this just be the timing still out?

One more question, on the back of the motor under the flyweel on the 84 evinrude, there is a square shaped computer chip.What is that? and what does it doo? i checked our evinrude book that we got from the local library but i cant seem to find it in there.

Any help is appreciated Thank u in advanced

 

[ezeke]

Re: 84 V4 90 hp Evinrude swap?

You may want to look at the parts diagram for your engine and ignition to see if you can identify the square part. Just go to this thread, navigate to your motor and look at the ignition diagram. http://epc.brp.com/default.aspx?brands=ej&lang=e

You need to replace the flywheel to crankshaft key with a OEM replacement and torque the flywheel nut to 100 to 105 Ft. Lbs.

The key controls the timing and if broken will cause erratic firing and unpredictable results.

Proper torque on the nut maintains the necessary bond between flywheel and shaft. Each time the key shears, the damage increases until it won't work at all, so it is imperative that the proper torque and a reliable torque wrench is used.