The breaker points saga continues and cam play

[jeffersonsharp]

I started a thread a couple weeks ago about trouble I was having with Sierra points. I determined the problems was Sierra points are worthless so I ordered oem points and now I’m having problems with them. With the Sierra points they would barely adjust to just touch at the cam bottom making them impossible to adjust in spec. The oem points don’t have that problem but even with the points pressing together I get no continuity between the contacts. I checked continuity from the wiring screw to the base contact and it was good then I checked the rocker contact and nothing. Even with the base pushing the rocker almost a quarter inch, no continuity. So I ran some sand paper between the points then and got good continuity for a bit. I ran a pristine piece of paper between the points and went to adjust them and the continuity was gone. Looking at the contacts it appears they aren’t coming together completely square. This is my first real experience with points so maybe there’s a process to them I don’t know. Should I have to sand the points until they come together square? Also the timing cam as a little play, a couple to a few degrees. Is that normal? The motors are 1957 Johnson 35 hp. Any advice at all? Thanks

[chris-p]

What sort of sandpaper?

You don’t want the granules stuck to the face of the points, or you will totally destroy continuity and get no spark.

I like to use a points file. Regardless, after you have dressed them thoroughally, blow off with compressed air. Then dip business card or paper stock in acetone, and run that through, then blow with air again. That should bring back spark. Even new points I dress to clean them up.

[jeffersonsharp]

The paper I used was 400 grit. I don’t know what the abrasive is but it’s black in color. These are brand new points. Would I be able to get a points file at the local parts store? Should the points come together perfectly square? I would assume they should but wouldn’t adjusting the points alter that. After I dragged the paper through the points a few times I really doubt there was any grit in there. Is it normal to have to dress brand new points? Thank you for your help.

[garry-in-michigan]

The super white printer paper and many business cards are impregnated with Titanium dioxide – which is an insulator. I always clean new points. You never know how they have been stored. . . 🙂

[jeff-register]

I use Acetone as a final cleaning then check sync 180 & use a meter closely. Pay attention to detale on how the insulation isolating washers are correct.
Just fixed a windshield wiper motor that was newly rebuilt. They left a feed wire off????? Might be a bent crank? + clean your feeler gauge too.
Mags must be clean to work well,

[amuller]

First, you say: "With the Sierra points they would barely adjust to just touch at the cam bottom making them impossible to adjust in spec." The rubbing block is not supposed to be in contact with the cam at the "bottom." The only measurement of significance is the point gap when the rubbing block is on the high point of the cam. (For a precision job you would like to measure the angular position of the crank when the points open, which you can do with a pointer type timing tool or by setting the flywheel on and marking the opening point on the rim.) So I suspect that you are wrongly condemning the Sierra points here. (Which is not to say they don’t have other shortcomings.

As for cleaning points: most sandpaper is made of aluminum oxide, which is an insulator, or silicon carbide, which is usually a conductor. Interesting comment about Ti02 as an insulator. A motor that’s been sitting may have a hardened oil film on the points. You can use a fine file and this is good if there is significant metal to be removed, but will not leave a very smooth surface. I usually use a strip of silicon carbide paper (the dark gray stuff, usually) doubled over to get both sides, followed by a strip of manila folder paper wet with a solvent. Best with well-used points is to take them apart and dress the surfaces on something flat like the edge of a table saw table. I like to get both points shiny-new looking and slightly convex, and aligned for contact in the middle of the pads. It takes a few minutes but they are generally as good as new. Points used to be made of platinum, or tungsten, or other expensive but durable materials. Not sure what’s used in today’s point sets.

[jeffersonsharp]

Ok I grabbed a point file at oriley. So, how much material do I need to remove? Should the points contact each other completely parallel. Also does anyone know if there should be play in the cam or do I have an undersized pin. The cam on the other engine has play to so I suspect that that’s normal, but I’d sure like further confirmation. Thanks again for all the help. Oh and btw I’m not using a feeler gage, in using a timing tool.

[amuller]

if the points are new you shouldn’t need to file them, just clean them. Unless, maybe, they are very "old stock." They should have parallel contact and it’s sorta normal to bend them a little to get there. I would use feeler gauges to get them in the ball park, then refine the adjustment with a timing light or tool.

[jeffersonsharp]

Thanks all for the help. I bent the base to get them contacting parallel as much as possible then filed them a little to clean and square them. I then used a residue free electric parts cleaner and some not too white paper to finish them up. I then adjusted them using the timing tool and got them breaking just past the first timing mark( I made sure to only turn them clockwise, not that the impeller is a concern with the gearcases currently being removed, but to make sure the cam play didn’t cause any errors. I’m getting excited to start these engines for the first time soon. Hopefully by the weekend. Again thanks for all the help. 😀

[jeffersonsharp]

Amuller, I didn’t see your first post before my last, good info there. As far as bending the points to get them parallel, it seems that can only be done vertically. I was having contact on the edge neerest the outside of the mag plate with a slight gap at the inside if that makes sense. The Sierra points would barely make contact even at the bottom of the cam and adjustment cam screw turned fully closed. It’s hard to break contact at the timing marks when you can hardly make contact at all. The upshot is the points could not be adjusted far enough to not break way early (I.e. Point gap way to large at top of cam and fully closed on adjuster cam screw). This was both sets of points that I installed and I have no reason to believe it wouldn’t be the other two still in the package. The problem seems to have been just sloppy tolerances. I’m not sure what kind of abrasive was on the sand paper I was using it was 400 grit and dark grey/black. I think I read somewhere that you should never use emery cloth on points as it contains carbon and will lead to pitting but I guess the carbon in silicon carbide is probably chemically bound so as not to cause a problem. I was worried my paper might be emery after reading that. Anyway I think I have it licked now. Thanks again.

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