702 Ignition system wiring

[RedRanger 1,468]

Just bought a 702.  PO removed all wiring from tractor.

I'll be rewiring to oe specs with on/off key and push button start.

I'm buying new parts and have the schematic from here.

I've found the cole hersee plunger switch, but trying to figure out which keyed switch I need.

How many amps run through the keyed switch?  Looks to me all that runs through the key is power to the coil?  Correct?

So how many amp switch is safe?  I've found 10A and 50A switches.

 

That said, looks to me that the push button switch powers the S/G directly from the battery.  So the 702 will crank over even if the key is off?  Correct?

Won't fire, obviously since the coil would not be powered, but do these crank even with the key off?

 

Thanks.

 

[953 nut 51,536]

Both of your presumptions are correct. I doubt that the current flow to the ignition coil would be more than one or two amps, perhaps "Saveoldiron" will chime in with an exact number. Just a light duty two position on/off key switch will work.

[RedRanger 1,468]

Low amp through the key is what I thought, but didn't want to assume.  Thanks.

 

Should I be considering any fuses?

Edited November 25, 2015 by RedRanger

[ri702bill 7,274]

Red:

 

Yes, all the current goes thru the momentary starter switch while cranking the engine. You CAN add a solenoid and replace the 2 position keyswitch with a  3 position one and wire it like it was an 854.

The old 2 prong Cole-Hersee switch is kind of neat, though ......... Both the 702 and 854 wiring diagrams are available here on the Forum.

 

Bill

Edited November 25, 2015 by ri702bill

[RedRanger 1,468]

3 hours ago, ri702bill said:

Red:

 

Yes, all the current goes thru the momentary starter switch while cranking the engine. You CAN add a solenoid and replace the 2 position keyswitch with a  3 position one and wire it like it was an 854.

The old 2 prong Cole-Hersee switch is kind of neat, though ......... Both the 702 and 854 wiring diagrams are available here on the Forum.

 

Bill

 

Kind of Neat.  I agree!  I've got the diagram  Thanks!

[Save Old Iron 1,563]

On 11/24/2015, 5:29:51, RedRanger said:

So how many amp switch is safe?  I've found 10A and 50A switches.

 

 

 

If you mean the "ignition" switch, 10A is safe, but make sure the switch is rated for 10 amps DC, not AC. Big difference.

 

The 10A switch will easily handle 3 -4 amps of current thru the ignition coil. If you start to wire in lights, etc, go for a larger 20 -25 amp DC rated switch.

11 hours ago, ri702bill said:

Red:

 

Yes, all the current goes thru the momentary starter switch while cranking the engine. You CAN add a solenoid and replace the 2 position keyswitch with a  3 position one and wire it like it was an 854.

The old 2 prong Cole-Hersee switch is kind of neat, though ......... Both the 702 and 854 wiring diagrams are available here on the Forum.

 

Bill

 

If you are not 100% set on originality, Bill's recommendation to add in a 3 position ignition switch and a starter relay energized SG motor is definitely the way to proceed.

 

May be even cheaper $$ wise to make the change.

Edited November 26, 2015 by Save Old Iron

[RedRanger 1,468]

Is this AMP gauge a correct original to a 702 or has the original been swapped out?  I'm accustomed to seeing SW gauges in these.

 

 

[ri702bill 7,274]

Red:

 

Yes, that is the original correct style for a 702. I did swap mine for a later chrome bezel style, only because the needle "bounces" too much at anything less than wide open throttle.

 

A couple of other things - don't forget to look at the frame attachment plate to the Uni-drive. If the tractor did much plowing as mine did, some or all of the 4 mounting holes can be cracked due to torsional stress twisting the frame. Same goes for the lower cast iron steering mount - one or both ears can be broken off. Sometimes hard to see on a 702, as there is a bent strap that goes from the hood stand under the dash over the top of the ears. Part of owning a Round Hood ..........

 

Bill

[RedRanger 1,468]

23 minutes ago, ri702bill said:

Red:

 

Yes, that is the original correct style for a 702. I did swap mine for a later chrome bezel style, only because the needle "bounces" too much at anything less than wide open throttle.

 

A couple of other things - don't forget to look at the frame attachment plate to the Uni-drive. If the tractor did much plowing as mine did, some or all of the 4 mounting holes can be cracked due to torsional stress twisting the frame. Same goes for the lower cast iron steering mount - one or both ears can be broken off. Sometimes hard to see on a 702, as there is a bent strap that goes from the hood stand under the dash over the top of the ears. Part of owning a Round Hood ..........

 

Bill

Thanks Bill.

I've got this tractor in pieces right now and from what I've seen, the frame shows very little wear or abuse.

I do have to fix some play in the steering and the upper steering shaft bushing/bearing.  No cracks though.

That AMP gauge looks period correct, but the black bezel almost looks new, so I was wondering.

Thanks for the info.

Steve