Wobbly armature plate old OMC

[andyman2010]

Hey guys,

I got my old 1956 Sea King up and running with all new tune up parts but she has a intermittent miss when running. The armature plate is wobbly. First time I've worked on a motor like this but I imagine the points wont hold timing rattling around like that

I've read about smacking the brass support plate at the 12-3-6-9 clock positions. This seems a little unorthodox to me. What is the best way to deal with a wobbly armature plate?

Has anyone used washers or some type of spacer to eliminate the wobble between the aluminum spacer and brass support plate? Any real world experience would be appreciated.

Kind regards,

Andy

 

[kbait]

Re: Wobbly armature plate old OMC

I found this:

(Magneto Armature Plate)
(J. Reeves)

If the armature plate has a a loose fitting, wobbling motion (the plate that the points, coils etc are attached to), it is usually caused by a slightly worn support ring. This allows the point setting to change erratically as the armature plate turns.

The cure is to remove the armature plate so that the support which is attached to the powerhead with 4 screws is visible. Then, with a screwdriver and hammer, or some tool of your choosing, and looking straight down at the support ring, make an indentation at what would be called the 12, 3, 6, and 9 O'clock positions. Install the armature plate and check for a smooth turning wobble free movement.

You may need to do that procedure a few times to obtain the proper fit (not too tight, not too loose), but it's worth the effort.

Use a small amount of anti corrosive grease between the aluminum ring and the brass support plate and also on the brass bushing of the armature plate when all is well.

 

[andyman2010]

Re: Wobbly armature plate old OMC

Thanks Kbait!

I found the same post on several sites. Im just a little leary hammerin' on the bracket and was curious to how others may have fixed this issue.

I will give the hammerin a go as there is a boat salvage yard not too far from me if things go wrong. Hehehe.

I guess the theory is bending the ring bolted to the motor just enough to take out wobble but still allow movement. Im gonna try my bucket O washers first and see if I can engineer an more subtle appproach.

I will post back for anyone else who may need this info.

 

[F_R]

Re: Wobbly armature plate old OMC

First make sure the brass hub isn't broke loose in the armature plate.

Second, make sure the retainer ring under the brass ring is right side up. It goes flat side up.

Third, ok now go ahead with the hammer. The worst you can do is destroy the ring.

If you really, really want to fix it, there is an improved armature plate and retainer parts. They are use on later model 40hp motors, 1970-ish. Kind of pricy.

 

[andyman2010]

Re: Wobbly armature plate old OMC

Thanks F_R!

I will check the aluminum ring under the brass plate it just may be upside down. Flat side up, got it!

I made a mark on the brass ring so I knew which end was up and positioning, but not the aluminum ring. I was curious if I installed backward. The more I think about it im thinkin' I did.

Ill post back after I get her back on the workbench. Thanks again guys!

 

[1946Zephyr]

Re: Wobbly armature plate old OMC

Yea, those rings are easily obtainable, since just about every OMC used them from 1951, on up into the 70's. I wouldn't even bother peening indents into yours. If it's worn that badly, I would just pick up another good used ring and ameture plate, at the local yocal salvage yard. They shouldn't be much money to replace.

 

[andyman2010]

Re: Wobbly armature plate old OMC

Well the ring was upside down. "Flat side up"

Thanks again F_R!

Took her apart in 10 minutes and flipped over aluminum ring and wobble is completely gone. Ring is solid and no hammerin'. I cleaned the points again with acetone while apart and double checked my coils/wires. Fires right up!

It seems to backfire a bit at slow/low idle. It will hum along for 8-10 seconds then a slight miss/backfire that slows the idle down, then picks right back up. I checked the spark with an inline spark tester and getting good spark to both cylinders so I assume its fuel related.

I ordered a new fuel pump last night and will see if that is the culprit.

I am using an old OMC steel tank that has visible rust on the exterior and had set for many years. Should I be worried about corrosion in the tank causing me issues, clogged feeder tube? Or should I just scrap the old tank and replace with modern plastic?

 

[F_R]

Re: Wobbly armature plate old OMC

Give the slow speed needle a tweak toward rich.

If the tank is rusty inside, there are plenty of used ones around. Opinions and feelings vary concerning plastic ones. I have one of each in my boat. They both hold gas.

 

[tmcalavy]

Re: Wobbly armature plate old OMC

If the tank is clean inside, you're probably all right...for now. If not, replace it. Might also consider pulling and cleaning the carb, check the fuel pump output and fuel lines from tank to carb.

 

[1946Zephyr]

Re: Wobbly armature plate old OMC

Is that the old 12hp model? Pretty good old motors and just as good quality as any Johny/Rude.

 

[andyman2010]

Re: Wobbly armature plate old OMC

Yes it's the 12 hp. I really like the cowl/side panel design. Reminds me of that 50's flaired tail lights. Really cool.

Thanks for the feedback. I followed the secret sticky guide for carb adjustment and it runs really smooth at low speed idle. When I put her in gear and rev up it bogs down and smokes quite a bit. I tried the same adjustments with the high speed valve and gets a little better but bogs down and does not want to take the gas. It does not die but won't rev up.

In neutral it revs up fine but not in gear. I have replaced primer bulb/hoses/fuel lines/points/condensers/coils/plugs/wires/rebuilt carb.

All I can think of is the fuel pump and that I'll replace this weekend. Although I did install the ring upside down hehehe. Maybe I missed something on the carb. Held upside down blew into intake float/needle valve working. Soaked overnight cleaned all parts well. I did not punch out the silver cap. I was worried about the new one fitting correctly. Maybe full O crud?

I will post back after I get the pump on. Thanks everyone. I appreciate you tak ing your time to share your earned knowledge.

 

[1946Zephyr]

Re: Wobbly armature plate old OMC

Check the carb adjustments.

1 1/2 turns out (from lightly seated) on the low speed

3/4 turn out on the high speed.

Once the needles are set, then adjust the knobs in a halfway point from the stops, so you'll have a half turn each way to work with. Check the packing nuts, so the needle doesn't turn loosely. Once the motor gets warmed up good, then you will likely turn each needle in a 1/8 of a turn for smother operation and an 1/8 of a turn out for cold starting.

 

[F_R]

Re: Wobbly armature plate old OMC

Where are you running this thing? In a barrel? That might be the only thing wrong with it. It may be inhaling its own smoke. If I am correct in this assumption, put it on a boat and adjust it there. It just might surprise you.

And stop revving it up in neutral. Those aluminum connecting rods weren't designed to be tortured.

 

[andyman2010]

Re: Wobbly armature plate old OMC

Well upon futher inspection I did not install the new float spring. The old one did not have one. The new should. I also discovered the assembly diagram with the rebuild kit does not show too much detail. Wait for it. Wait for it. I have a really nice tan cicular rubber gasket on my tray. I put a red fiber washer on the carb in it's place. Boss gasket I see later. Well live,learn, rebuild.

I have not been holding her open in neutral. Just a few quick revs.

I found this really nice easy to see diagram. Maybe this will help someone as new to carb rebuild as me. Here is a link to the site I found it on. Nice detailed pics and explanations: http://www.outboard-boat-motor-repair.com/johnson/Evinrude%20Johnson%205.5%20HP%201954-1964%20Carburetor%20Tune-UP.htm


Well i'll have it apart and together later. I'll let y'all know.

 

[andyman2010]

Re: Wobbly armature plate old OMC

Thanks everyone!

I took the carb apart again and this time put the BOSS gasket where it belongs. Repacked the high-speed/low-speed needle valves, double checked my float/needle. WOW does she ever run so smooth. It's just amazing. Now I just need to replace my fouled plugs for an even smoother running motor

I have one small issue. The shift linkage seems to be off. Neutral should be center position on shift lever. It is all the way back. The center and forward position both appear to be forward.

Before I grab a wrench is this an adjustment somewhere concerning the shift rod in the lower end? It was this way before I turned the first bolt. When I re-assembled the lower end I simply put the shift rod back into the coupler with needle nose and tightened the bolt.

Maybe I need to disconnect the shift linkage. Put shift knob in neutral(center postion), and then re-connect linkage? Any ideas?

I painted it this weekend, attached are some photos.