Odd points system on a 1946 Firestone 3.6 hp outboard

[jwcole04]

I got about a dozen non running small outboards from my marine mechanic a few years ago and was able to get most of them running. They all produced spark however so I never had to deal with electrical issues.

I was given a Firestone (Scott-Atwater) outboard motor Code no 133-6-1065 Stock no 10-A-111 3.6 hp - I think it's a 1946. No spark.

My understanding of points is that they stay in contact until the camshaft forces them apart at TDC producing spark. This points system does exactly the opposite (see pics and zoom in). These points stay apart until the lever hits the relatively short flat part of the cam and they close.

Can anyone explain this to me?

Thanks!

 

[racerone]

Is the cam up side down?

 

[jwcole04]

Thanks for the response racerone. I tried turning the cam upside down but it has a tapered woodruf key type thing that only allows it to only go on one way. If you could turn it upside down it changes nothing. There is still the relatively short flat section with the rest being round, holding the points open.

 

[Chris1956]

I think there were other points systems like that. Maybe old Mercury's? The question is "Does it work"? I presume it does not need a condenser.

Also, the Johnnyrude V4 battery and magneto distributor motors had one coil, one condenser and 2 sets of points. The cam lobe was set up to open one set of points early and then open the second set of points when the cylinder was to fire. The points alternated which one opened first.

 

[3rdtimesthecharm]

Ask on A.O.M.C.I. Dot org. They have an ask a member forum that’s free.

 

[racerone]

I think that old magneto used a condenser.

 

[jwcole04]

Ask on A.O.M.C.I. Dot org. They have an ask a member forum that’s free.

Thanks - I'll give that a try.

 

[racerone]

To me it appears that there is nothing " special " here.----Which way are you turning the crankshaft?----Clockwise ?

 

[jwcole04]

Sorry to waste your time racerone. The problem is I'm getting 2 opposing explanations of how points work:


1.

2. • Points Closed (Charging): As the engine turns, magnets in the flywheel pass the ignition coil, generating electrical current in the coil's primary winding. While the point contacts touch (are closed), this electrical circuit is complete.

• Building a Magnetic Field: The current flowing through the closed circuit builds up a strong magnetic field inside the ignition coil.

• Points Open (The Spark): A small mechanical cam, plunger, or crank lobe pushed by the engine's rotation forces the points apart at the exact moment the spark is needed.

As I said in the first post, I haven't had to deal with spark issues. I tested the coil and condenser with a multimeter and the seem ok, but I don't know if I'm seeing the proper numbers - also cleaned the points, flywheel magnets and coil.

Maybe the wires are bad.

I'm turning the crankshaft clockwise

Thanks for your help!

 

[Chris1956]

Gee, how did you test the condenser?

I guess I am surprised that you have a condenser since it's main function is to absorb the electrical arc that occurs when the points open, and feedback the stored energy to the coil, helping (immensely) with generating spark. Since your points apparently close to initiate spark, I am not sure why you need one.

FYI, my Mercury OB ign coils are specified to be .02- .04 ohm on the primary coil. Nearly a dead short which a crummy voltmeter may not read correctly. The secondary winding is spec'd at 800-1100 ohms. I would expect your coil to be close to those specs.

 

[racerone]

Good luck with this motor.

 

[jwcole04]

I don't know where to get parts or specs for this motor. I'll try some things but am skeptical and will probably run out of patience. Here's a wider shot.

btw I got my first boat in 81 and have been fishing Puget Sound and the Strait every summer and fall since. By watching videos and messing around with small outboards I was able to fix my 87 Johnson 50hp and save a lot of money.

There was a good Coho run this fall - here's a picture of a good day's catch. Daily limit for my wife and I is 4.

Thanks again

 

[Mc Tool]

Thats just a normal spark on opening of the points , granted the dwell period appears to be quite short