1989 85 hp to a 1990 hp outboard force

[jazzatoi]

Does anyone know i could replace a 1990 Force powerhead with a 1989 force 85 hp powerhead ?

I was told to ask Frank Acampora here on Forums,


Thanks

Jesse

 

[Bigprairie1]

Re: 1989 85 hp to a 1990 hp outboard force

Does anyone know i could replace a 1990 Force powerhead with a 1989 force 85 hp powerhead ?

I was told to ask Frank Acampora here on Forums,


Thanks

Jesse

Hang in there Jesse, Frank is the guy to ask...and he is probably on his way.
BP

 

[Frank Acampora]

Re: 1989 85 hp to a 1990 hp outboard force

Yes! The mounting is the same and the crankshaft splines are also the same. You did not say if the 1990 was a 3 or 4 cylinder but it doesn't matter if you are not trying to use electronics from a three on a four or four on a three. They have different triggers. However the 89 and 90 (3) cylinder electronics are exactly the same. Therefore if both engines are three cylinder, it is a direct swap and you have your choice of which electronics you want to use--assuming both engines are complete with electronics.

To access the mounting bolts you need to remove the rear shroud. remove carbs, starter, electronics, and head to make the block lighter and prevent damaging delicate components. 9/16, 1/2, 7/16, and 3/8 wrenches are just about all you will need. There are six 9/16 head bolts on the front of the match plate and six 9/16 nuts under the rear shroud.

The only problem you will have is corrosion around the mounting studs where they pass through the midleg. They tend to be tight and you will need to carefully pry at the pry points. Sometimes it can be frustrating. Because of this, you will need to remove the lower pan for room.

If you leave the exhaust down-tube connected to the block, you will not need a new base gasket, just a little black RTV silicone.

The block is a bit heavy so it if you don't have a lift, it pays to have a friend help. To remove or reassemble, the exhaust down-tube has a flange that interferes with the water tube mounting so the whole block and down-tube must be twisted a bit to clear it. That's where the extra hands help.

While you have the block off, look on each side of the leg flange at the front motor mount bolts and washers. They tend to rust. Remove the bolts and replace with same length 3/8 stainless bolts. Replace the washers with extra thick stainless washers if you can find them. You may need to grind them a bit to fit. If you can't find them, coat the washers with a good amount of RTV silicone just before you mount the replacement block. Replace the bottom mounting 3/8 bolts with stainless also.

 

[newbie4life]

Re: 1989 85 hp to a 1990 hp outboard force

Yes! The mounting is the same and the crankshaft splines are also the same. You did not say if the 1990 was a 3 or 4 cylinder but it doesn't matter if you are not trying to use electronics from a three on a four or four on a three. They have different triggers. However the 89 and 90 (3) cylinder electronics are exactly the same. Therefore if both engines are three cylinder, it is a direct swap and you have your choice of which electronics you want to use--assuming both engines are complete with electronics.

To access the mounting bolts you need to remove the rear shroud. remove carbs, starter, electronics, and head to make the block lighter and prevent damaging delicate components. 9/16, 1/2, 7/16, and 3/8 wrenches are just about all you will need. There are six 9/16 head bolts on the front of the match plate and six 9/16 nuts under the rear shroud.

The only problem you will have is corrosion around the mounting studs where they pass through the midleg. They tend to be tight and you will need to carefully pry at the pry points. Sometimes it can be frustrating. Because of this, you will need to remove the lower pan for room.

If you leave the exhaust down-tube connected to the block, you will not need a new base gasket, just a little black RTV silicone.

The block is a bit heavy so it if you don't have a lift, it pays to have a friend help. To remove or reassemble, the exhaust down-tube has a flange that interferes with the water tube mounting so the whole block and down-tube must be twisted a bit to clear it. That's where the extra hands help.

While you have the block off, look on each side of the leg flange at the front motor mount bolts and washers. They tend to rust. Remove the bolts and replace with same length 3/8 stainless bolts. Replace the washers with extra thick stainless washers if you can find them. You may need to grind them a bit to fit. If you can't find them, coat the washers with a good amount of RTV silicone just before you mount the replacement block. Replace the bottom mounting 3/8 bolts with stainless also.

Not that I know anything about this situation, but it's a 3 cylinder -- and it may or may not be for sale by me.... The engine is complete, with the electronics.

When I was asked if it would work, I thought it would, but I don't like to give a fake answer so I get my sale... I knew that if anyone were to know the answers, it'd be Frank. The guy is amazing...

Quick Frank, what's the square root of 8?

 

[Frank Acampora]

Re: 1989 85 hp to a 1990 hp outboard force

Um--off the top of my head---2.82--um--84--2.8284271! If you want more accuracy than that, I'll need to use a calculator.

 

[MostlyHrmlss]

Re: 1989 85 hp to a 1990 hp outboard force

I want to do the same thing, but put a '90 powerhead on a '79, both 85hp. Does the age difference make this more difficult?

 

[MostlyHrmlss]

Re: 1989 85 hp to a 1990 hp outboard force

From what I've been reading around here, the powerheads should swap out physically, the problem being a possible mismatch in the shaft splines. I can't find a reference that tells me what the sizes and spline counts are for various years, can anyone point me in the right direction?

 

[Frank Acampora]

Re: 1989 85 hp to a 1990 hp outboard force

NOPE--No problem. The drive shaft splines are the same and the complete block will just drop in. You will have the advantage with the newer block of more precise timing since the 90 does not have a distributor and I think in 79 they still used distributor ignition.

Be aware though: If you want to use the 79 ignition and flywheel on the 1990 engine, you must change the alternator stator mount and you will find it will not fit. There was a special part made for this to convert the old Magna-Power II to distributor ignition. If you can find one, it costs 80 bucks. (AHEM! I have two!) However, it is possible to have a machine shop turn down the distributor ignition stator mount to fit. Then you need to drill and tap four 3/8 X 16 holes for it AND drill and tap the distributor mounting ears on the block.