Old style points in Wisconsin engine

[Donald]

Trying to get a Wisconsin engine going in an old Hobart generator/welder.

It's a two cylinder with a distributor, points condenser, coil.

It's been decades since I have dealt with an engine with points.

The engine turns over, there is +12V at the ignition switch.

I turned it over spraying in starter fluid and no pop or anything. Put in one of the spark testers inline with a spark plugs and nothing. It's dark in barn so I would see a spark.

The +12V for ignition goes to the coil or the dist. to the points.

Where to check with my DVM? Coil should show ?? on primary and secondary for ohms? The condenser is only to cut back on arcing across the points so I can disconnect for initial testing? What should the condenser test on my capacitor tester?

 

[BigCahuna]

I would file the points and check the gap. The condenser might be bad and if it is it won't run, but the good thing is they're cheap. Then turn the key to the on position, and jump the points with a screwdriver. You should see a spark if everything is good. If not, change the condenser. You should be able to get it started with 6 volts if you needed to, the condenser will supply the juice needed to run.,,

 

[Donald]

What about the coil? How to test it?

Will any automotive condenser work?

 

[Donald]

I would file the points and check the gap. The condenser might be bad and if it is it won't run, but the good thing is they're cheap. Then turn the key to the on position, and jump the points with a screwdriver. You should see a spark if everything is good. If not, change the condenser. You should be able to get it started with 6 volts if you needed to, the condenser will supply the juice needed to run.,,

Where will I see a spark? At the points?

 

[Trav]

Trying to get a Wisconsin engine going in an old Hobart generator/welder.

It's a two cylinder with a distributor, points condenser, coil.

It's been decades since I have dealt with an engine with points.

The engine turns over, there is +12V at the ignition switch.

I turned it over spraying in starter fluid and no pop or anything. Put in one of the spark testers inline with a spark plugs and nothing. It's dark in barn so I would see a spark.

The +12V for ignition goes to the coil or the dist. to the points.

Where to check with my DVM? Coil should show ?? on primary and secondary for ohms? The condenser is only to cut back on arcing across the points so I can disconnect for initial testing? What should the condenser test on my capacitor tester?

+12V (or system voltage) goes to the coil, coil neg to the points.

 

[Gyro Gearloose]

Use your DVM to measure the voltage across the breaker points with the points open and with the points closed. If you are getting voltage supply to the coil you should see 12 V across the breaker points when open and close to zero volts with the points closed. (This measurement is across the points themselves, not to ground). If you measure significant voltage across closed points they are burned, corroded, or coated with oil and otherwise not conducting. Spray the points with brake cleaner and pull a strip of 400 grit sandpaper between them to clean them up and provide temporary restoration. The purpose of the condenser is to give the primary current a place to go as the points begin opening rather than create an arc which would take longer for the current flow to fizzle out. The faster the current flow can be stopped in the primary the higher the voltage that will be induced in the secondary. You will only get a very weak spark from the coil if any at all without the condenser in the circuit. It is necessary for proper functioning.

Plug a sparkplug directly into the coil and check for output directly from the coil as well. Distributors, rotor buttons, and wires are all subject to developing short circuits.

 

[spasm3]

I would start by replacing the condenser, if the points are gapped properly.

 

[Donald]

I would start by replacing the condenser, if the points are gapped properly.

I assume I can use any old condenser for 12V autos.

 

[spasm3]

I don't see why not, but I've not tried it. I have not worked on points in 30 years.

In a jam I have set points gap with a folded business card, when I did not have a feeler gauge on the road.

 

[mk378]

Turn key on you should measure battery voltage at the + primary terminal of the coil and either the same voltage or near zero at the - terminal depending on the position of the points. Bump the starter a few times to check that. Do not meter the high voltage terminal, but as others said hold a grounded test wire near it and see if you can make sparks by grounding the points while the points are open.

The condenser is about 0.1 uF as I remember. Best way to test the coil is by substitution. Practically any coil will work even one from a typical electronic system.

 

[Lubener]

The points need to be lightly burnished with fine emory cloth. If an engine was stored off of the compression stroke, the points will be open and likely have corroded some (it doesn't take much) and you will not have any spark as a result. The gap likely would be .020 but an incorrect gap will not affect spark but it will affect the timing of it. I would just open them up and burnish them and recheck for spark, the gap likely is ok if you don't have a feeler gauge handy and I would leave the gap setting alone if you cannot do it right with a feeler gauge.. That's what I put my money on, it would be much less likely to have a coil or condenser failure.

 

[Cujet]

As mentioned above, the old condenser (really a capacitor) can 'dry out' over time, and the result can be a poor spark. It's not quite as easy to find one in today's market, but they are still available. Lawn mower shops will likely have some version that will fit and work. But, I'd guess the points need cleaning.

Also, if you have power, you can mimic the action of the points by, a) leaving the points open, b) simply touching the points wire to ground about once a second, with a jumper lead or screwdriver, c) observing the spark plug 'spark' when you lift your wire.

 

[Donald]

As mentioned above, the old condenser (really a capacitor) can 'dry out' over time, and the result can be a poor spark. It's not quite as easy to find one in today's market, but they are still available. Lawn mower shops will likely have some version that will fit and work. But, I'd guess the points need cleaning.

Also, if you have power, you can mimic the action of the points by, a) leaving the points open, b) simply touching the points wire to ground about once a second, with a jumper lead or screwdriver, c) observing the spark plug 'spark' when you lift your wire.

It has a normal rotor and dist cap on top of points. So easier said than done. A dist cap for only 2 spark plugs. They could have just given both cylinders a spark at same time if 100% opposite in the 4 cycle which I assume they almost certainly are.

The condenser checks on my HF DVM to be 266 nF. Which is within range for an ignition condenser.

 

[mk378]

Test for sparks directly from the coil. Don't involve the cap and rotor.

 

[berniedd]

X2 on all the above. Esp mk's suggestion above. The rotor or the distributor could be defective and shunting the high voltage to ground.

A standard ignition condenser would work for you. IIRC the condenser in my 1968 Beetle was rated at 0.25 ufd 600 volts.

 

[Silverado12]

FWIW I've used a matchbook to set the gap in a pinch but try sanding the points first. Common problem when a motor sets for a while.

 

[Donald]

I got the finest emery cloth I had and sanded the points. And the rotor a little. Still no spark.

I looked at the coil and the terminal for the +12V is not threaded but rather looks like its for some kind of a tiny press on connector. But they had a ring terminal and a nut that of course would not tighten.

Can I just get a car coil from 1970s? I do not see a ballast resistor, unsure if it matters. The ballast resistor could be stuffed some place I cannot see it. The coil is on the opposite side of the engine from the distributor and the high voltage wire snakes over the top of the engine under the top cover.

 

[zrxkawboy]

It’s really best to know if the coil might have a built in resistance. Is there a number on the old coil that could be crossed?

 

[ragtoplvr]

+12V (or system voltage) goes to the coil, coil neg to the points.

View attachment 30106

The drawing is not sufficiently detailed. Most old point type systems use a ballast resistor. The solenoid coil has a “relay” terminal that is used to bypass the ballast resistor while cranking. When this terminal fails, there may be no or very low voltage to the spark plug. Ballast resistors and or “relay” terminals can fail



Check for a ballast resistor or length of resistor wire leading to the coil and a second wire coming from the starter.