Need Help with 861 ignition/timing

[Mad Farmer]

Believe what you want to believe. The excess arcing from the higher voltage and current pits the contact faces of the points. Yes it will also shorten the life of the coil, but that is usually from 10 or more years down to 2 or 3 years. The points will become pitted to the point they won't have the correct gap much sooner than that.

Point pitting is caused by mismatched condensers.

 

[Texasmark]

Decades ago before I could afford Diesel tractors, I ran gassers. I had a foolproof way to set the points. Get the ignition setup so that the tractor would run on its own.......move the distributor CCW until it started belching and mark that point.....turn it back CW until the same thing happened. Set it in the middle. Never had a problem.

 

[Texasmark]

You are welcome
Glad I could help

Back in the 70’s when I was in USAF mechanics school we had a week of working on just such problems.
The first part of the week you had to get a motor running and the second part of the week you did things to the motor so it would not run for the next class to fix.
Things like putting clear scotch tape under the points so the points could not ground were common.

John that is absolutely hilarious.......what a mean trick....LMAO.

 

[showcrop]

Who says you can't treat an old dog new tricks! John in LA , Your step by step instructions did the trick. If you are not already writing books to help people like me "That know just enough to be dangerous" Then you should be. Keith from Ohio was dead on with his advice The brass bolt that goes thru distributor was shorting out the wire coming from the coil. I ran a single wire from the minus side of the coil directly to the points I ended up running a 2nd wire to the plus side of the coil, that was fed from the "I" terminal on the starter relay. She fired right up Thanks to all for your input.

That insulator in the distributor wall has, over the years, been the cause of a lot of no starts here at YT.

 

[Texasmark]

Point pitting is caused by mismatched condensers.

The size of the capacitor needs to be large enough to slow the rate of rise (when the points pen and the coil keeps shooting current down the circuit) to below the arcing potential yet fast enough to do it and allow time for the coil to dump its load at the highest operating RPM.

 

[Btzj02]

The size of the capacitor needs to be large enough to slow the rate of rise (when the points pen and the coil keeps shooting current down the circuit) to below the arcing potential yet fast enough to do it and allow time for the coil to dump its load at the highest operating RPM.

In my world if the coil and the condenser are balanced perfectly the VAR flow will be zero thus minimizing the arc. VARs are an imaginary number created by an engineer years ago to help understand AC power transmission. In the control center where I worked none of us could explain exactly what a VAR was but we worked with it everyday. Good job Texasmark!

 

[Texasmark]

In my world if the coil and the condenser are balanced perfectly the VAR flow will be zero thus minimizing the arc. VARs are an imaginary number created by an engineer years ago to help understand AC power transmission. In the control center where I worked none of us could explain exactly what a VAR was but we worked with it everyday. Good job Texasmark!

Thanks.

 

[pomester]

There is not a true 12 volt system out there that I am aware of.
Either a ballast resistor reduces the voltage or the coil has extra windings in it to reduce the voltage. (What some call a 12 coil or no resistor needed).
It’s like that on factory installed 12 volt systems or 6 to 12 volt conversions.
The reason some systems use a ballast resistor over a 12 volt coil is so they can bypass the resistor supplying a full 12 volts to the coil during cranking.

So points only see 12 volts during cranking in any system. Providing 12 volts to the points all the time will promote sparks jumping the gap and pitting as the points open and close.

The only 12 volt system ford had before 1965 was the diesel so there was no 12 gas tractors.
Not real familiar with the after 1965 tractors but I believe all of those were 12 volt.

But let’s say one tractor same size model year ect is 12 volt and one is 6 volt. Both would use the same coil points and condenser from the factory. The only difference would be the 12 volt tractor would have a ballast resistor.

So - I have been looking at ballast resisters (aftermarket) and there are different ranges of resistances. I see everything from .3 to 1.8 ohm. How does one size the resister to the ignition system?

 

[john in la]

So - I have been looking at ballast resisters (aftermarket) and there are different ranges of resistances. I see everything from .3 to 1.8 ohm. How does one size the resister to the ignition system?

A ballast resistor is matched to the coil to give a total resistance.
A true 12 volt coil has a resistance of between 3 and 4 ohms achieved by adding extra wire windings in the coil.
A resistor of 1.5 to 2 ohms will usually get your 6 volt coil to have a total resistance of 3 to 4 ohms so it can be used in a 12 volt system.