851 Ignition Oddity

[john in la]

When there is a will there is a way.

Get the car solenoid with the grounded base.
Isolate the solenoid base from the tractor metal so it can not ground.
A simple block of wood would do that.
Now hook keyed power to the small terminal on right.
Hook small left terminal to coil bypassing resistor.
Hook the wire from starter button on trans to solenoid case mounting bolt.

Now you have a setup that allows the solenoid to provide 12 volt power to the coil during cranking and preserve the neutral safety starter button.

 

[used red MN]

When there is a will there is a way.

Get the car solenoid with the grounded base.
Isolate the solenoid base from the tractor metal so it can not ground.
A simple block of wood would do that.
Now hook keyed power to the small terminal on right.
Hook small left terminal to coil bypassing resistor.
Hook the wire from starter button on trans to solenoid case mounting bolt.

Now you have a setup that allows the solenoid to provide 12 volt power to the coil during cranking and preserve the neutral safety starter button.

A cube relay would be far less complex. And
the recommended diode would be easier yet.

 

[Btzj02]

Why have you put this “mumbo jumbo” into a reply here? Now someone down the road is going to want to know how this is done. Someone will have to tell them they need a big dollar buc converter.

Because the last two tractors I worked on had 12 volt conversions that were done incorrectly and they both came with a box of burned out resistors and the PO's could not figure out why they were having so many electrical issues. If you believe it is Mumbo Jumbo than apparently you did not understand what I was saying. I don't think I recommended a Big Buc conversion I was simply pointing out that if you do a 12 volt conversion make sure you pay attention to the rest of the tractor not just the ignition.

 

[Duner Wi]

What both of you mention would bypass the neutral start safety system. Ford grounds the second terminal of the solenoid and feeds 12 volts to the other small terminal when the ignition switch is turned on.

Ole Fred, Please explain how a wire with diode from starter lug on starter going to coil + on a 12 volt negative ground system will bypass the neutral start safety system??
How about using a 6 volt solenoid energized by ground factory original system to energize a 12 volt solenoid with I wire terminal for start only. Now we could not inadvertently start engine while using starter to bump engine forward by using starter.

 

[Jim.ME]

How about using a 5 terminal ST 83 solenoid as referenced by JMOR in this old thread. It will give resistor bypass and use the original ground to engage the solenoid switch.

It is safest to pull the coil wire out and ground it when you just want to crank the engine over in all cases, in my opinion.

Old Thread.

 

[ole fred]

Ole Fred, Please explain how a wire with diode from starter lug on starter going to coil + on a 12 volt negative ground system will bypass the neutral start safety system??
How about using a 6 volt solenoid energized by ground factory original system to energize a 12 volt solenoid with I wire terminal for start only. Now we could not inadvertently start engine while using starter to bump engine forward by using starter.

I took "a push button switch that supplies battery voltage to solenoid" to mean that the solenoid supplied voltage to the starter. That would bypass the neutral start safety system. I was mistaken. I do like your method of running wire from the starter terminal to the coil with a diode. It is simple and not obvious to most folks. I will probably do that later. If I decide to sell the tractor, I doubt the buyer would ever notice.

 

[Ford4thousand]

Question, did you measure the resistance of the 6v coil to make sure it's really 6v? I had a tractor once that someone was running an unmarked 12v coil WITH a resistor and it caused weak starting until I verified the coil. Otherwise you should never need a diode on a single wire alternator unless you have some odd wiring.

 

[ole fred]

Question, did you measure the resistance of the 6v coil to make sure it's really 6v? I had a tractor once that someone was running an unmarked 12v coil WITH a resistor and it caused weak starting until I verified the coil. Otherwise you should never need a diode on a single wire alternator unless you have some odd wiring.

Nope, I haven't gotten around to it yet. It will probably be spring - or at least when it gets warmer.

 

[Sean in PA]

Question, did you measure the resistance of the 6v coil to make sure it's really 6v? I had a tractor once that someone was running an unmarked 12v coil WITH a resistor and it caused weak starting until I verified the coil. Otherwise you should never need a diode on a single wire alternator unless you have some odd wiring.

The diode being discussed is to prevent the bypass wire from feeding voltage back to the starter, not for the charging circuit.

 

[Ford4thousand]

The diode being discussed is to prevent the bypass wire from feeding voltage back to the starter, not for the charging circuit.

I gotcha, that seems like a bandaid for a problem that shouldn't exist, why bypass anything in a normal wiring situation? Not trying to be argumentative because you're more knowledgeable than me, but any tractor should start immediately, if not, it's only a couple of other simple things, with the first thing to look at being too much resistance if they ran a resistor AND a 12V coil with internal resistor. Second is just plain bad wiring. I can appreciate the OP has come up with a temporary work around though

 

[ole fred]

I gotcha, that seems like a bandaid for a problem that shouldn't exist, why bypass anything in a normal wiring situation? Not trying to be argumentative because you're more knowledgeable than me, but any tractor should start immediately, if not, it's only a couple of other simple things, with the first thing to look at being too much resistance if they ran a resistor AND a 12V coil with internal resistor. Second is just plain bad wiring. I can appreciate the OP has come up with a temporary work around though

I agree with everything you say, but you can't beat shooting almost 12 volts to a 6 volt coil to get a super hot spark. True, if everything is correct, you shouldn't need to, but what if everything isn't up to snuff. Like last week when the temperature was below zero and the tractor had been sitting for a couple of months.

 

[Duner Wi]

I agree with everything you say, but you can't beat shooting almost 12 volts to a 6 volt coil to get a super hot spark. True, if everything is correct, you shouldn't need to, but what if everything isn't up to snuff. Like last week when the temperature was below zero and the tractor had been sitting for a couple of months.

GM for one IH for 2 was shooting 12 volts to the coils in the 1950s. I don't know who else. Doesn't hurt a thing that I know of.

 

[ole fred]

My MF TLB gasser is also. It's a 70's something - I think. Maybe 60's.

 

[Sean in PA]

Ford used a 6 volt coil with a resistance wire and a bypass wire from the factory on the 1965-1975 thousand series gassers.