How to change coils, set points on Old OMC's-with pics

[jbjennings]

Here's a little info. for those who may need it on how to get good spark on an old OMC (50's, 60's, and some 70's models).
I hope some real experts like F-R will double-check my post, pretty please so noone gets any bad info from me or if I forget something.....


Here's a pic of some cheap tools and such you'll need to remove the flywheel and such:

Make sure you use hardened 1/4-20 bolts, available at any decent hardware store. Screw them in the 3 holes that you will see after you take the ring off that the pull starter pawls grab onto when starting it.
then use a 5/8 socket to tighten the harmonic balancer puller. Be sure the flat side of the puller is up. A pic of the puller setup is shown in the second pic. You'll have to tighten the heck out of it sometimes until the flywheel pops off. The flywheel hole is tapered which makes it wedge down when you tighten the flywheel nut. Never beat on the flywheel to remove it or you will ruin the flywheel! Be sure to tighten it to specs. with a torque wrench when you reinstall it or your flywheel key might shear off.

 

[tashasdaddy]

Re: How to change coils, set points on Old OMC's-with pics

number 8 harden bolt, that fit the holes in flywheel, different Hp have different sizes. screw them in 7/16th inch. you may have to smack the center bolt of puller, to pop flywheel. never pry on the edges, or hit flywheel. all items must be total clean and oil free, when reassembled.

 

[jbjennings]

Re: How to change coils, set points on Old OMC's-with pics

Another try for the tools pic.:redface:

 

[jbjennings]

Re: How to change coils, set points on Old OMC's-with pics

Now for the under-flywheel stuff:

1. Check your coils for any obvious problems like cracks and such. Usually when they're bad, you'll know it! But not always. If they're old, change 'em!
To change the coil:
Unscrew the 3 screws that hold it to the base.
detach the wire from the points and the ground wire from the right hand screw on the coil. Pull the coil out, detaching the spark plug wire from it.
Replace with new coil.
Check the old wire for corrosion in the metal core. IF it's corroded, the best bet is a new wire, but at the very least get about 1/2 inch of slack and snip off 1/2 inch of the end of the old wire so that you see good metal in the core of the wire to attach to your new coil. It's very important that you get the wire all the way into the coil. You may need to take off the armature plate to get to the bottom of it and loosen the spark plug wires from the bottom to get some slack or just to replace the wires. Be sure to check the old wires to be sure there are no cracks or scuffs on the insulation of the wire or it WILL find a way to short out and you won't have spark.

To set the points:

Put on the flywheel nut and tighten it until you turn the flywheel until the points cam is under the rubbing block. Most of the points cams say "top" on them. Position the "O" in "top" directly under the points cam. Make sure the cam is down (it has a spring under it) and check to see if your gap is right in your points. The gap is .020 on most 50's motors I've seen. You should be able to easily slide the .020 feeler guage in the points gap without much binding. Just a LITTLE friction is all you should feel. Enough to know that the points are touching the feeler gauge but not tight on it. If it's too loose or too tight, then adjust the adjusting screw on the points. I've labeled it in the pic below. You will probably want to replace the points since they're cheap. But, you might want take a points file and clean off any corrosion on them and reset the gap. This usually is good enough. Make sure the points are clean. Even a fingerprint can mess them up. It's not a bad idea to replace the condensers, too, at this point. They're cheap and they DO go bad sometimes.

COIL NOTATION!!!!!!!!

Make sure when you reinstall your coils, they are not protruding past the mounting boss or you WILL booger them up when the flywheel magnet comes by and smashes them! I'll try to post a picture of the right and wrong way for them to be later.

Good luck....
JBJ

 

[jbjennings]

Re: How to change coils, set points on Old OMC's-with pics

Here's a pic of my new 6$ spark tester from autozone.....HANDY!

 

[jbjennings]

Re: How to change coils, set points on Old OMC's-with pics

Here's a pic of my new $6 spark tester from autozone.....Handy!

Also, a couple of pics of the proper way to mount the coils--a common mistake...

Hope this helps,
JBJ

 

[Rick.]

Re: How to change coils, set points on Old OMC's-with pics

jbjennings.
Thanks for you effort on this. I think it is a great idea and a real confidence booster for those who are unsure of what they are doing. If I could make a couple of comments: 1. The red writing in the pictures is hard to read. Especially the picture where you write over the mount on the old coil. 2. the position of the coils on the mounting boss. I changed coils on a friends motor a few years back and as I remember his old coils were just proud of the mounting boss. I checked them with a feeler gauge and mounted the new coils proud by the same amount.(it wasn't more than a few thou.) Again, I think your work here will be appreciated by many. Rick.

 

[jbjennings]

Re: How to change coils, set points on Old OMC's-with pics

Thanks for the comments, Rick. I'll fix those pics. I got in a hurry in case the youngster with the 10hp was needing them. Will check on the other stuff and fix as well.
JBJ

 

[56 rude]

Re: How to change coils, set points on Old OMC's-with pics

Now for the under-flywheel stuff:

1. Check your coils for any obvious problems like cracks and such. Usually when they're bad, you'll know it! But not always. If they're old, change 'em!
To change the coil:
Unscrew the 3 screws that hold it to the base.
detach the wire from the points and the ground wire from the right hand screw on the coil. Pull the coil out, detaching the spark plug wire from it.
Replace with new coil.
Check the old wire for corrosion in the metal core. IF it's corroded, the best bet is a new wire, but at the very least get about 1/2 inch of slack and snip off 1/2 inch of the end of the old wire so that you see good metal in the core of the wire to attach to your new coil. It's very important that you get the wire all the way into the coil. You may need to take off the armature plate to get to the bottom of it and loosen the spark plug wires from the bottom to get some slack or just to replace the wires. Be sure to check the old wires to be sure there are no cracks or scuffs on the insulation of the wire or it WILL find a way to short out and you won't have spark.

To set the points:

Put on the flywheel nut and tighten it until you turn the flywheel until the points cam is under the rubbing block. Most of the points cams say "top" on them. Position the "O" in "top" directly under the points cam. Make sure the cam is down (it has a spring under it) and check to see if your gap is right in your points. The gap is .020 on most 50's motors I've seen. You should be able to easily slide the .020 feeler guage in the points gap without much binding. Just a LITTLE friction is all you should feel. Enough to know that the points are touching the feeler gauge but not tight on it. If it's too loose or too tight, then adjust the adjusting screw on the points. I've labeled it in the pic below. You will probably want to replace the points since they're cheap. But, you might want take a points file and clean off any corrosion on them and reset the gap. This usually is good enough. Make sure the points are clean. Even a fingerprint can mess them up. It's not a bad idea to replace the condensers, too, at this point. They're cheap and they DO go bad sometimes.

COIL NOTATION!!!!!!!!

Make sure when you reinstall your coils, they are not protruding past the mounting boss or you WILL booger them up when the flywheel magnet comes by and smashes them! I'll try to post a picture of the right and wrong way for them to be later.

Good luck....
JBJ

good tips JB!I would like to add add one if i may for the coils,i found using a straight edge helps a lot ,just line up the boss and the coil together and your there.so far ive done several motors and never had a problem atall using this method as i dont have acess to the coil ring tool.

 

[rjezuit]

Re: How to change coils, set points on Old OMC's-with pics

Good job. May want to add be sure the wires are tucked away from the flywheel on reassembly, and do one side at a time, that way the other side is good for reference on reassembly. Also not to nit pick but they are properly called "grade 8 bolts" If you do not use the correct terminology you may confuse the place you are getting them from. #8 bolts are a size (like 8-32 or 1/4-20) 1/4-20 is 1/4" outside diameter and 20 threads per inch. Many times grade 8 bolts are black because they are heat treated and then black oxide coated. Rick

 

[asdasc]

Re: How to change coils, set points on Old OMC's-with pics

This VERY helpful and much appreciated. Thanks for your hard work.

I was going to do a how to like this for rebuilding the lower unit also, but it takes so much time.

With all the commonality and popularity of the Johnson 18-20-25HP from 53-73, it almost makes sense to give the 'family' of motors thier own subforum, with another for the same vintage motors 15HP and down, and then another for the BigTwin on up.

 

[LIGHTFOOT]

Re: How to change coils, set points on Old OMC's-with pics

Great info guys. I just bought a 1966 9.5 Evinrude off E Bay that "Runs Great", or so the ad said. When I put it in the tank, it had no spark on number one, so this thread will be very helpful to me for changing the coils and installing a tune up kit. Thanks again for the great job!

 

[coolguy147]

Re: How to change coils, set points on Old OMC's-with pics

Thanks for the comments, Rick. I'll fix those pics. I got in a hurry in case the youngster with the 10hp was needing them. Will check on the other stuff and fix as well.
JBJ

lol thanks for mentioning me and u guys should reply to my thread anyone any help would be good. acually im going to napa right now on my bike to check and see if i can order the coils condensers and points

 

[coolguy147]

Re: How to change coils, set points on Old OMC's-with pics

lol this would be a great thread in the frquently asked questions area

 

[coolguy147]

Re: How to change coils, set points on Old OMC's-with pics

awsome post

 

[asdasc]

Re: How to change coils, set points on Old OMC's-with pics

Hi JB, I tried to send you a PM on this, but your message box is full!

First of all, I want to tell you that the work you did on is awesome, and needs to be preserved in the FAQ. One thing that we may want to fix is the text on the pictures to make it more readable. If you want, I can help. Send me the original pictures and I can add the text to them so it can be read clearly.

On the tools, can you send me the text you used so that I get it right? I can't read it at all on the posted pics.

Thanks,

Steve

 

[jbjennings]

Re: How to change coils, set points on Old OMC's-with pics

I've been lazy...... Maybe this one is a little better. Will try to fix more, too. I still have to post a pic of my $6 spark tester---handy!
thanks,
JBJ

 

[asdasc]

Re: How to change coils, set points on Old OMC's-with pics

Thanks, looks great, but you forgot to point out the icy cold beverage. That is as important as any tool on the tray!

Also, you should point out that they are Grade 8 bolts, rather than #8 which could be confusing to some.

 

[wildmaninal]

Re: How to change coils, set points on Old OMC's-with pics

COIL NOTATION!!!!!!!!

Make sure when you reinstall your coils, they are not protruding past the mounting boss or you WILL booger them up when the flywheel magnet comes by and smashes them!
Good luck....
JBJ

I have had the flywheel break off one of the coils out of the mounting bosses and which it bent the points on the one side as well on my '57 35hp E'rude.

Is there a fix for a stripped bolt hole let's say for the points? Anybody had that problem?

Forgive me if I missed it but you might want to add that the flywheel needs to be torqued to specification or you might shear the woodruff key. Also upon finishing the coil installation and points setting, check the woodruff key for worn spots and replace if necessary, check the flywheel slot that meshes with the key for worn spots as well for this will also cause a shearing of the woodruff key also. Also you want to make sure that it is super clean under the flywheel, no dirt, metal shavings, grease, etc etc.

 

[asdasc]

Re: How to change coils, set points on Old OMC's-with pics

Is there any way to get this put into the FAQ section?