1976 25 hp Points question

[69 Alumacraft]

Re: 1976 25 hp Points question

Ran my 69 today after replacing spark plug wires, point and condensers, runs great, just needs motor mount rubber pieces that are way over priced, may have to make my own any body have experience with that. My GD 76 is still in limbo.

 

[69 Alumacraft]

Re: 1976 25 hp Points question

Hey Howard, Read that post about adding a driver coil, I have an extra that I replaced for no good reason, so may install it and see what happens. On another note have you ever replaced the rubber motor mounts I have a 69 that needs them desperately but they want 30$ a piece on line? I feel like I can make them out of an old tire or something instead. Any thoughts?

 

[samo_ott]

Re: 1976 25 hp Points question

Which engine mounts? Most are the same on many engines and you can get em off another engine easily.

 

[samo_ott]

Re: 1976 25 hp Points question

Ran my 69 today after replacing spark plug wires, point and condensers, runs great, just needs motor mount rubber pieces that are way over priced, may have to make my own any body have experience with that. My GD 76 is still in limbo.

Went to run my '69 today and then realized I had left it in the water too long and had to chop it out of the ice! sigh...

 

[69 Alumacraft]

Re: 1976 25 hp Points question

Still can't get a consistent spark on the bottom hole? EVERYTHING is new and been taken out and put back several times. I have switched the leads and both coils produce a good spark when hooked up to the number 1 cylinder. Disconnected grounding switch, I thinking I must have a bum flywheel, it seems to be magnitized on both sides as it will grab a screwdiver. I read a post about adding a second driver coil to the empty spot on the arm plate and I think I am going to try it. I have the one I replaced and it is not cracked and tests out good on my ohm meter, just need the correct screws. I plan to mirror image it to the other one. http://forums.iboats.com/showthread.php?t=279981
Any thoughts?

 

[kfa4303]

Re: 1976 25 hp Points question

I may be wrong, but I believe you can convert your current ignition to the older style, "universal" magneto set up, with two coils, and two sets of points and condensers. They're extremely reliable and easy to work on and virtually all of the parts are interchangeable with other OMC motors of the era. When complete, it should look like this:

 

[69 Alumacraft]

Re: 1976 25 hp Points question

That is what my 69 sportster looks like. The armature plate for the 76 is different there is no holes for the spark plug wires to screw into the driver coils. Also, are the magnets in the flywheels the same. I agree the older style is easier as I rebuilt the entire system in a couple of hours and it runs great. The 76 has me in a tizzy and the only thing I can think of is the flywheel has lost its magnetism. Can this happen? Does this happen, I have only seen one post that even mentions this. I have totally taken apart the system, cleaned and replaced all components and I can only get a weak spark or no spark on the the bottom cylinder which leads me to believe the flywheel is to blame, is this impossible? The top jumps 3/8 gap with a bright blue pop, so the driver coil is good, right? It is brand new!?

 

[OptsyEagle]

Re: 1976 25 hp Points question

I mentioned this upthread a while back.

If I were you I would pull your flywheel. Disconnect the wires from the point (The 3 wires for Driver coil, point and condenser). Attach a continuity tester (multimeter) to the point wire of the bad cylinder's point. The other wire of the multimeter should be attached to a ground spot on the powerhead. When the point is closed you should be hearing or seeing full continuity from the multimeter. Now very slowly rotate the drive cam until the point just opens (continuity should stop). Then keep rotating until the continuity comes back (point closes). The objective here is to ensure that the points close properly and open properly and only open ONCE per 360 degree revolution. I had a brand new point from Sierra that would open properly at the right time and then open again about 0.001" about 80 degrees later. Don't know how this happened but it did and it caused me a big headache. The cylinder still fired but pulsated badly at higher throttles.

Anyway, it's a good test to verify your points are clean and operating properly.

When the point "just opens", in addition to the above, I would also hold the flywheel above the driveshaft, aligned as good as possible with the key and ensure the timing marks are now aligned. This will then confirm that your timing is correct as well. Remember 0.020" gaps just get you in the ball park. Those timing marks are the actual timing spot you want.

Lastly, now that your multimeter is out, I would check the continuity of your ground by attaching one lead to the powerhead bolt (ground) and touch the top of the flywheel, the bad point's ground and anything else that needs to be grounded. You should get full continuity when you do this. If you don't you have a grounding problem.

 

[69 Alumacraft]

Re: 1976 25 hp Points question

I mentioned this upthread a while back.

, I would also hold the flywheel above the driveshaft, aligned as good as possible with the key and ensure the timing marks are now aligned.

Not sure what you mean, this could be my issue, ignorance, how do I align the the timing marks, I thought there was only one way the flywheel can go on and one way the armature plate can go on.

 

[F_R]

Re: 1976 25 hp Points question

He is talking about setting the points according to WHEN they open, instead of HOW FAR they open. That is the correct way to do it. There is a timing fixture tool made for that purpose (I make them). There are also timing marks on the flywheel that serve the same purpose, but obviously you can't access the points with the flywheel in place. The timing fixture gives you access.

 

[OptsyEagle]

Re: 1976 25 hp Points question

Yes, FR's method is easier and more accurate, but you would need the special tool. PM him if you are interested. I believe he provides them very cheap.

My method, however, is simply this. There are timing marks on both the flywheel and armature plate. I think one is an indent and the other a line. When the cylinder fires the line on the flywheel should be exactly between the indent on the armature plate. This is the perfect spot for your piston to be when the spark fires. When you set your points to 0.020", the time the spark actually fires should end up being very, very close to this spot. To verify, you can run my test. You know the spark fires JUST as the point open the slightest amount. That would also be when you lose continuity of your circuit in my test above. So to be sure your points are set to fire at the right time, you can rotate the cam until the point just opens or when the continuity ends and then stop turning the cam at that spot. That's why you want to turn the cam as slowly as you can. Now, without moving anything, take the flywheel and visually align it with the cam (as you said it only goes on one way) and now look at those two timing marks. The line should be between the indent. If it is, you are perfectly timed. If it is not, you are firing at the wrong time. To fix it, when it is out of time, you just adjusting the point gap higher or lower. It may end up that 0.018" is the perfect gap for your motor (although if that is the case, I doubt you would even notice the difference if it was then set to 0.020").

When you have the point gaps set, so the spark will fire at the right spot as explained above, you can then check what that gap is for all future reference.

I don't think your problem is timing, but it doesn't hurt to get it set right, all the same. I do think you might have a defective point. If your point was opening even just a little, when it should be shut, it will prevent the condenser from building and holding the charge that it needs to give you a spark, at any time. This could be your problem. It may not, but I would do the test just to set your timing right, anyways.

 

[F_R]

Re: 1976 25 hp Points question

There is no doubt that merely setting the points at .020" is good enough. A more thorough understanding of the system explains why it is preferrable to set them by timing rather than gap. There is a voltage reversal as the flywheel magnets go from the first two legs of the driver coil and proceed to the second and third legs. The points should open at the exact optimal time during that reversal. Setting them at .020" is close, timing it gets them right on the money. You don't need to buy a tool for just one job, just wanting you to know why it is important.

 

[HighTrim]

Re: 1976 25 hp Points question

I personally bought one from Frank. Great tool, wish I had it much earlier.

 

[69 Alumacraft]

Re: 1976 25 hp Points question

ok thanks for the info, I am having a hard time finding the timing mark on my flywheel all I see is " 6 DB 1" on top above the teeth. Is that the mark? I see the double lines on the armature but not on flywheel. t
Thanks for explaining the timing thing, I understand now. I am using a mutimeter set on the ohm 200 setting. Is this correct? I have all winter , not giving up. My 69 runs great with the two driver coils and no externals, i am tempted to convert the 76 to the same way. Armature plate is different but I bet I could drill a couble of holes for the leads. Is the flywheel different?

 

[F_R]

Re: 1976 25 hp Points question

Use the lowest available ohms setting when working with the points and primary circuit.

I haven't actually looked for the marks on one of those particular flywheels, but they should be there---I think. Turn the shaft till the cam is just about to open one set of points, then carefully slip the flywheel on. The timing mark should be close by the double lines on the armature plate. There should be another one 180 degrees around the flywheel for the other set of points.

Your '69 has one set of magnets in the flywheel, your '76 has two sets of magnets. I'm not sure what would happen if you use a '76 flywheel on a '69 magneto. Probably fire a second spark at the bottom of the piston stroke, I assume (?) Hey, you're a good guy to find out and report back. Put the '76 flywheel on your '69 motor and see what happens. It may backfire and poot, but at least you will know what is causing it, and can put it back the way it was.

 

[OptsyEagle]

Re: 1976 25 hp Points question

I never owned a 1976 25Hp but I do have a 1975 9.9HP that I would think would look close to the same as yours. You can see the marks from the two arrows. On the flywheel I have two marks for each point (4 marks in total). I believe the other two are for electric starting motors, where mine is a rope start. I have no idea why they would use different timing marks but I stopped pondering that a long time ago.

Anyway, do you have any marks that look like these?

 

[AlTn]

Re: 1976 25 hp Points question

You might consider swapping the points....any change?...no, swap the condensors...any change? no?....I'm outta ideas.as it seems you've had about every combination except physically swapping the coils instead of swapping just the wires from the exciter as maybe a coil ground is bad on that #2 cylinder

 

[jmendoza]

Re: 1976 25 hp Points question

Here is one thing I ran into when changing points, and that is that some come with a lacquer coating on the contact surfaces of the points that needs to be removed using MEK, acetone, or lacquer thinner. I do this before installing them by dragging strips of paper dipped in solvent through the points repeatedly, like about 10 times, using a fresh strip and solvent for each pass.
I had a problem where I got weak and intermittant spark after replacing the points, and it was because they had a clear protective coating on them I did not know about.

 

[69 Alumacraft]

Re: 1976 25 hp Points question

Thanks to all especially Oldman and F_R. It was a timing issues the bad cylinder was opened up too far, I found the mark, used my mutimeter and closed the point gap and eureka! Big blue sparks on both. We'll see what happens when she runs! Thanks again!

 

[oldman570]

Re: 1976 25 hp Points question

69 Alumacraft, Iam glad that you got it running, and that you have learned just how finnicky the electrical systems can be. Once they are set they will be good for quite some time. The worse thing I have found is that the longer a motor sets without being run, the more work it takes to get them back running. I try to run all my motors atleast once a month when I can, and always run them dry of gas. The gas system can be just as bad to repair as the electrical at times. Timming and sync of the motors is the key to a good running motor. I am sure F_R will tell you the same. Learning the Hard way has it's drawbacks, but one always remmbers what they have learned. If you have more trouble with it, come back, and all here will help you out as much as we can.

Have Fun boating and BE SAFE,
Oldman570