90hp Tower of Power rebuild...questions

[swamp-fox]

Hi everyone, I'm fairly new here and some of this is kind of new to me.
These are my '78 90 and 115 towers. I plan on taking the distibutor off the 115 and putting it on the 90. One of my questions is, why would the distributor go out on the 90 in the first place. My dad took the cap off and the inside was melted. I'm just looking ahead to see what else needs to be replaced.

Also before any questions on why I want the smaller hp running, is it has sentimental value. My dad bought it new in '78 so I'm going to redo everything on it. Also I'm 90% sure the top cylinder is out on the 115, this week I will do a compression check.

 

[Faztbullet]

Re: 90hp Tower of Power rebuild...questions

Was the potting in the trigger melted?? If so I would swap the switchbox also as the resister in switchbox may have shorted internally shorting trigger.

 

[swamp-fox]

Re: 90hp Tower of Power rebuild...questions

I think the answer is yes. When I took the cap off there was the black sticky stuff (like the swithchbox has but melted) on the points. It had dripped on the rotor and through the windows.
That is good to know because I found a NOS switchbox, but was hesitant to buy. Now I think I will.

 

[swamp-fox]

Re: 90hp Tower of Power rebuild...questions

I think I want to change the coil also. That is what I call it anyway, but everywhere I look it gives me a switchbox-coil combo looking thing. That is the coil that runs the center wire up into the distributor right?

 

[Chris1956]

Re: 90hp Tower of Power rebuild...questions

Swamp, You need to get your terms correct, as you have confused me. The switchbox is mounted on the cowling support, external to the distributor. The distributor has a hall-effect trigger, which uses a disc with 6 windows. The trigger straddles the disc. The coil is mounted on the base of the crankcase cover, and is wired to the switchbox and the dist cap.

 

[swamp-fox]

Re: 90hp Tower of Power rebuild...questions

Sorry, I guess I lost you in the description of the black sticky stuff?

These are not the best pics but

this is the switchbox


and this is the coil


Right?

 

[Chris1956]

Re: 90hp Tower of Power rebuild...questions

Yes, Those pictures are titled correctly.

You do not have any points. BTW - The rotor is non-removeable, very fragile and costs $200+ to replace.

 

[swamp-fox]

Re: 90hp Tower of Power rebuild...questions

I don't have a pic of the distributor but it's toast anyway. I'm taking the whole distributor off the 115 and putting it on the 90hp.


So were can I get a new coil? The one on iboats doesn't look right.

 

[carholme]

Re: 90hp Tower of Power rebuild...questions

fox;

http://www.crowleymarine.com/mercury-outboard/487.cfm

Gerry

 

[swamp-fox]

Re: 90hp Tower of Power rebuild...questions

Yep just found that one.

Thanks

 

[swamp-fox]

Re: 90hp Tower of Power rebuild...questions

So the next question is compression check. I will start by saying this. There is nothing to indicate that anything is wrong. It has never run hot and the last time it was running it was good, or at least nothing I could tell.
Since there is no distributor on it yet there is no way to do a conventional compression check right? I have been reading a little on leak testing. Are those really more accurate that a regular compression test? I think that might be the way to go since I won't have to turn over the motor.

I have been looking for a good reason to buy a air compressor and I would hate to put this thing back together, do a compression test and it fail....I guess my question is should I spend the money on a leak tester or is there another way?

 

[Chris1956]

Re: 90hp Tower of Power rebuild...questions

You only need a starter and battery to do a compression test. You can use some jumper cables to connect the battery to the starter and make it spin.

The cylinders should be 100+PSI and within 15% of each other.

 

[swamp-fox]

Re: 90hp Tower of Power rebuild...questions

Well thats what I thought, but I tried to do one on the 115. The spark plug wires were just hanging not connected to the spark plugs, so I thought no big deal. Because I don't need a spark just the starter to spin everything. Well it would not even spin, turn over or anything..... So I connected all the wires to the spark plugs and then it started spinning.

I just thought about it and I took the fly wheel off the 90 to change the stator...I will put it back on to do the test but based on my experiance above I don't think it will work without the distributor.

side note: the top cylinder was out on the 115 it had 90psi on the top cylinder and 125 on the other 5.

 

[swamp-fox]

Re: 90hp Tower of Power rebuild...questions

Ok here's a question. I am leaning towards just cracking the motor open anyway. I think I would like to change all the seals and gaskets at least.
Here is a few things I'm worried about

1. snapping bolts off- theres not to much anyone can help with here (wd-40 and kroil)
2. what should I change
If the cylinder looks good and not scorn, I know I should atleast put new rings..right?
Reeds? I've heard people change boyseen and pick up throttle response they never new they had
3. how hard is it? Ha Ha I know that's a good one that everyone ask...I've done everything else to the outside of a motor, just never
opened one up.
4. special tools?

 

[swamp-fox]

Re: 90hp Tower of Power rebuild...questions

Bump...

 

[swamp-fox]

Re: 90hp Tower of Power rebuild...questions

Can I use the fly wheel off the 115 of the same year and put it on the 90hp? The sticker is bad on the 90 and the 115 is still readable.

 

[Chris1956]

Re: 90hp Tower of Power rebuild...questions

As long as both motors have the distributor ign, the flywheels should be compatable. The crankcase bolts on that motor will not be corroded, however, there is no reason to open the crankcase, unless the compression is low.

Remove all spark plugs, Use jumper cables to connect the starter to a battery and take a compression test. If the results are good, fix the wiring and ign system, clean the carbs, install a new waterpump impeller and see how it runs.

Remember the starter is mounted in rubber, and that is why it has two cables on it. The upper cable grounds the starter to the block.

 

[swamp-fox]

Re: 90hp Tower of Power rebuild...questions

Yeah now that I'm thinking about, I started taking some of the 115 apart. Then when I got it to my new Apt. I decided to do a compression test just to confirm my suspition. On the 115. After I tried the compression test with the spark plug wires unhooked and it didn't work. I saw that wire hanging for the ground so I connected it and the put the wires on the spark plugs.

Well on the 90, the one I'm rebuilding, I have taken everything off the motor..fuel pump, pigtail wires, coil, distributor etc. It's just a bare block. Can I just put the flywheel back on and starter (grounded this time) and do the compression test? Do I have to put the carbs back on?

 

[Chris1956]

Re: 90hp Tower of Power rebuild...questions

No need to reassemble the block. Spray some oil into intake manifold just to lube everything up.

 

[swamp-fox]

Re: 90hp Tower of Power rebuild...questions

Ok well that sounds like a plan. I also sounds like a good reason to leave work early...