1977 johnson 140- 87 tnt and leg swap

[mpar2001]

Hey boaters, hopefully a few on here are knowledgable enough to help me out with my boat project, here goes, just the facts!
My 1977 140hp ran great all last season, but near the end the shifting became hard, and frequently jumped out of gear, then I read thats because i have the problematic hydraulic/mechanical shift. This motor was manual tilt/trim which makes it nearly impossible to pull up the motor in the water, and not much fun on dry land either.

My parts motor is a 1987 with VRO power trim/tilt and a good working bottom end. I have read on this forum you can swap the lower leg unit onto a 1977 if you swap the intake manifold over as the 87 manifold has the mounting boss for the different design of shift linkage. In theory this sounds simple enough, so I broke out the tooks and salvaged the parts off my 87 and realized theres a bit more to it than I thought.

Questions/potential problems with the lower unit swap:
1- Choke: 87 has electric pump choke, 77 has butterfly plates and a solenoid. Looks like the 77 solenoid will bolt onto the 87 manifold with 1 bolt, anyone care to comment? I would like to keep the 77 carbs with butterflys.
2- Fuel pump: Looks like all I have to do is take out the large slot screw from the 87 manifold, clean the paint out of the threads for the 2 mount screws, easy right?
3- Extra ports: the 87 manifold has extra ports for the primer tubes, and vro pump. Take out the fittings and plug them all off, no problem!
4- Any other potential problems I am overlooking?

Questions about the power trim swap
I have both the steering units sitting on the bench, bolting them up will not be a problem at all, its the wiring I'm not so sure about
1- I removed the solenoid box from the 87, not sure how I'm going to bolt it up to the 77 as the power pack above the bubble. I will probably just solder and extend the wiring harness and mount the box inside the boat, which leads to my next question...
2- There are 2 red wires coming out of the solenoid box that go to the power strip on the 87. What do these wires do, are they necessary, and if I move the solenoid box can they just be hooked up to the battery? Maybe they need to be extended and hooked up to the power strip on my 77, but which terminals?

Thanks a bunch for your help figuring out this swap, this motor is going to be fantastic when it is all put together the way I want it. The powerhead has very low hours and is very clean for a 77, but the hydromechanical shift is notorious for problems. Ive even gone to the trouble of stripping all the old flakey paint off, and will be painting the entire motor, cover, new decals. Its going on my 1979 campion alert, there will be a restore thread on the boat to follow soon! Yupp, I have a problem alright! I love boats!
Mike

 

[mpar2001]

Re: 1977 johnson 140- 87 tnt and leg swap

http://www.maxrules.com/graphics/omc/wiring/TnTwiring.gif
Been doing more research.. Looks like I am right about wiring up my Relay box for the tnt, the RED wire goes to battery positive, but what does the RED and BLUE wire do? the unit is a E110TXCUR, which I take it the C is for commercial, whatever that means.

 

[Will Bark]

Re: 1977 johnson 140- 87 tnt and leg swap

The "C" is the 8 in the model year 87, the R means nothing to us since its a model run . Wish I could answer any of the other questions but you will have some great gurus to chime in, Good luck

 

[emdsapmgr]

Re: 1977 johnson 140- 87 tnt and leg swap

You will have to re-use the power trim solenoid box from the 77. It usually mounts under the rear engine splashwell and is wired direct to the battery, just like the engine. The two trim systems are incompatible. Your 77 uses a 3-wire trim motor, the 87 uses a two wire system. If you want to convert to an old style premix pump which will adapt to the pulse hose of your VRO, you can purchase a (new) old style pump from Bombardier. Get a 3-port pump. Part number: 438559

 

[mpar2001]

Re: 1977 johnson 140- 87 tnt and leg swap

My 77 had no power tnt, just manual send yourself to the emergency room tilt.
Looks like on the diagram the RED is for 12v for the relays and red/blue is the power for the switch. Why wouldnt I be able to just simply swap the entire tnt unit over, extend the wiring harness for the relay box, put it under the transom and viola it should work! What is it that makes them incompatible? connect the red and red/blue up to the battery and it should work.
Thanks for the help, Im not saying youre wrong just trying to fully understand this before I move forward ordering parts etc.
EDIT to clarify, I unbolted the entire unit off the motor complete with steering tube, transom bracket etc.

 

[mpar2001]

Re: 1977 johnson 140- 87 tnt and leg swap

Heres a few pics to help.
1-campion: stay tuned for the build thread on that, totally off topic!
2- fuel pump: this is my 438556 fuel pump with the 87 manifold. looks like it should bolt up if the slot screw is removed. I see the 438559 pump has the extra port to hook up with the VRO pulse line, do I need to use the 559 pump or will the 556 pump work?
3- intake manifold: Green circles are the tubes that I am thinking I will remove them and plug them off. The Red circle is where Im thinking the fuel pump will bolt up, take out the large slot screw and clean the paint out of the threads. Can I get a pulse off that port with the slot screw or does it need to come from the VRO pulse line.
4- tnt: left is the power unit from my 87, right is my manual from 77. They appear to be pretty similar, its a bit decieving as they are on different angles in the pic, But it looks like I should be able to bolt it up to the mid section of my 77. I havent tried yet as Im sanding/painting my motor and dont want to get grease on it! Then I will use the 87 relay box and extend the harness as necessary(I am great with wiring) and mount my relay box near the battery, hook up the power, and as long as there isnt a reason my it wont bolt up I should be laughing!

Thanks for the help guys, this project is occupying my mind 100% of the time, cant wait to get my restored boat back on the water this spring.

 

[emdsapmgr]

Re: 1977 johnson 140- 87 tnt and leg swap

You can use either pump-your option. If you pull the screw out of the block to use the pump you have, you'll just have to block off the old VRO port. If you use the pump pictured, you will need the fiber gasket, part number 303615. I'd probably try to get the recirculation system working on that intake. The 87 factory manual will have the proper routing for the hoses. You may need to test/replace the one-way brass vavles. That recirc system will help with idling on that engine. I think you are on the right track with the trim system. The only problem is that the 77 140 does not have the mounting holes for the trim box on the back of the engine. If your 87 is a 110 hp engine-with the bubble back exhaust, you could swap the outer exhaust manifold from the 87, which will have the holes.

 

[phillnjack2]

Re: 1977 johnson 140- 87 tnt and leg swap

The trim wont cause any problems swapping it over.
The 140 1977 had the trim relays in the boat, so its a dead easy swap over.

And just out of curiosity what sort of milage are you getting from the 140 ?

like how many gallongs per hour or whatever as a friend of mine has the same engine,and we have not found it too bad
so far,but only been testing it on short runs till fully ready for a proper blast.

phill

 

[mpar2001]

Re: 1977 johnson 140- 87 tnt and leg swap

making good progress getting this figured out!
I was out in the shop last night and just to be sure, I bolted the trim n tilt up to make sure it fits, which it does, its all just a matter of wiring to get it functioning- mount the relay box inside the boat, extend wires as necessary.

I would usually get around 3-4gph at a good cruise speed, about the same as my old 110. Not too bad all things considered.

Is that what those little tubes are, the recirculation system? I will have to look into that tonight. I thought that was the choke system on this motor.

 

[mpar2001]

Re: 1977 johnson 140- 87 tnt and leg swap

Was just out in the shop, and as it turns out my 110hp had alot of those hoses hooked up very wrong! some went to the choke solenoid, some to bypass ports, it was all crossed up! That clears up a few things, I have a few options now.

1- keep the recirc setup instead of plugging it, and to compensate the jetting I should also be using the 1987 carbs and the solenoid fuel enrich style primer instead of the butteryfly and solenoid, which eliminates having to figure out a way to mount the solenoid from the 1977. Hook up the wire from the keyswitch to the solenoid and we are laughing! Only problem is my 87 carbs need a good cleaning.
2- keep it all 1977, if the motor lasted this long as runs as good as it does, why change anything? Plug off the recirc plugs in the manifold, and figure out how to mount the solenoid for the choke butterflies. Use the 77 carbs, choke, and keep it simple, after i mount that solenoid..

Keep it coming, the motor build is coming together, and I now can order the parts I need to finish it.

 

[emdsapmgr]

Re: 1977 johnson 140- 87 tnt and leg swap

I prefer the newer carbs-as long as they are the same size throats. Check out the size of the carbs-cast onto the front flange of the carbs. The later solenoid permits you to run fogging oil or engine tuner into the fuel system much easier via that schrader valve. As long as you have the intake off, why not consider adding a set of composite reeds? The reeds help with smooth idle, improved midrange and maybe a hundred or two rpm's on top.