Mixing and matching Johnson 140 powerhead to johnson 200 mid section and lower unit

[stonebreaker]

I have a working 84 Johnson 140 V4, and I just bought a boat with a blown 76 Johnson 200. The 140 has a 25" midsection, the 200 has a 20" midsection with a lower unit that has a nosecone and low water pickup.

First question: Can I put the 140 powerhead on the 200's midsection?

Second question: The 200's powerhead has a crack in one cylinder. If the 140 powerhead won't fit on the 200 midsection, would it be reasonable to trade the working 140 to have the 200 repaired? Would that be a reasonable trade?

There is a hydraulic jackplate on the boat, but I'm not sure if it can compensate for the additional length of the 140's midsection.

[evilrude 1]

The 140 will fit but you need to use the adapter/tuner as well.

[stonebreaker]

What adapter/tuner? I've been drag racing for 15 years, but I just moved to a lake house last year and I'm just learning about boat motors.

[racer]

Shift on the lower is completely different as is the ratio between the 4/6 in the years you mention

[evilrude 1]

Racer is right---the intake from a older v4 (73-76) would need to be swapped as well or just find a 20" drive shaft for the v4 lower unit.
As for the tuner/adaptor... its the thing your block mounts to.

[stonebreaker]

Racer is right---the intake from a older v4 (73-76) would need to be swapped as well or just find a 20" drive shaft for the v4 lower unit.
As for the tuner/adaptor... its the thing your block mounts to.

What about adding a setback? I can weld aluminum, it just dawned on me I could fab up a setback. Since I'd be doing that anyway, is there any formula that would tell me how far to make the setback and how high to mount the motor?

[evilrude 1]

Set back or set-up all depends on a lot of variables
-style of boat tunnel of V bottom
-weight
-what your doing with it (top speed only or skiing)
-any natural set -back built into the boat
-length
-the type of propeller (s) you will be using
-steering system (dont try to go 100 on a plastic pully and cable (with the spring) system.
as for a general "rule of thumb"---6" back = 2" up
-Hopes this helps-

[stonebreaker]

Well, the boat is a 1972 Cheetah 18'. It's a shallow vee hull with a rounded keel. The engine it had was a Johnson 200 that was in pieces when I went there. It had a nose cone with a low water pickup on it, and I don't know what the stock pistons look like, but the ones in the motor had domes that were almost hemispherical. I suspect the motor was hopped up pretty good.



I don't know what kind of steering system is on the boat, but whoever restored this boat put a lot of effort into it. The transom was reinforced with very heavy duty steel brackets that looked custom made from what looked like 1/4" plate steel. They were through-bolted through the transom and also the bottom of the boat. The boat has a 20 gallon built-in fuel tank.

I'm guessing the boat probably weighs around 2000 lbs. (fiberglass is heavy compared to aluminum). As for what I'm going to use it for, primarily just zipping around the lake in the afternoons when I get home from work, but also skiing when the kids are home from college.

Since I'm going to be somewhat limited on horsepower, anything I can do to improve efficiency will be done.

[stonebreaker]

...you also mentioned the 'type of prop'. What types of props are there, and how are they different?

[evilrude 1]

Nice boat
But I would be a little concerned about the steel plates,especially being bolted through the hull.
Make sure its is sound before adding any leverage to that transome.
If every thing is good I would start with a 10 inch set back plus your jack(it will have some set back aswell) you have a heavy boat for a crossflow v4 but it could work well. Just make sure you dont load that motor down with a big prop. Prop it for 6000+ rpm @WOT and use the best gas/oil poss.(ALWAYS!)
Crossflows need good fuel to survive. I would also make sure your timing isnt more than 26 deg reguardless what the manuals say.
I would guess high 40's-low 50's is what this hull was designed for due to that rounded "keel" and I would also recomend a dual cable steering system combined with solid engine mounts. Especially if you are going to jack it.
You will also need a good ss prop, I would try a omc raker-good bow lifter and good for getting on plane

[stonebreaker]

OK, I started reading about propellers and now I'm confused. Ordered this book:

[stonebreaker]

Went and picked up the boat on Friday, good news is that I bought the blown motor for $100. I figured I could make some money on parts, but when I took it by the local outboard engine shop, the owner said the engine really just needed a new piston and a bore on one cylinder. He said with the pistons it has, along with the aftermarket reeds and other go-fast parts, he figures the engine was making about 240 hp at the prop at 6000 rpm, and should push the boat to around 75 mph. So I think I'm going to put the 140 on it for now and have the 200 repaired when I can save up the bucks.