resistor or no resistor

[tom upton]

I just finished putting an 310 gas into a 88 oliver. Used a new delco alternator I had on hand. ( The one that still uses the external regulator) Wired it up per the diagram for 1850 gas which didnt specify a resistor from ignition to coil, however I am wondering if it is a typo in the IT manual as the diagram for 1750 gas shows a 2 -2.4 ohm inline resistor between ignition and coil, with everything else showing exact same as 1850. With tractor running I have around 9 volts on the distributor side of coil. Am I o/k to run with no resistor or will it eat up my points??? I struggle a bit with electrical so need help please.

 

[Jim.ME]

I just finished putting an 310 gas into a 88 oliver. Used a new delco alternator I had on hand. ( The one that still uses the external regulator) Wired it up per the diagram for 1850 gas which didnt specify a resistor from ignition to coil, however I am wondering if it is a typo in the IT manual as the diagram for 1750 gas shows a 2 -2.4 ohm inline resistor between ignition and coil, with everything else showing exact same as 1850. With tractor running I have around 9 volts on the distributor side of coil. Am I o/k to run with no resistor or will it eat up my points??? I struggle a bit with electrical so need help please.

Using a resistor or not depends on the coil, the 1750 may have used a 6-volt coil and the 1850 may have used a 12-volt coil. For a number of years around the change over from 6-volt to 12-volt systems many manufacturers continued to use 6-volt coils with external resistors, or resistor wires, on 12-volt systems. Unhook the primary wires from the coil and check the ohm reading across the primary terminals of the coil. 3 to 4 ohms it is a coil designed and internally wound to use on 12-volts and does not need an external resistor. Ohms in the 1.5 ohms is a coil wound for 6-volts and needs an external resistor for use on a 12-volt system.

 

[tom upton]

Using a resistor or not depends on the coil, the 1750 may have used a 6-volt coil and the 1850 may have used a 12-volt coil. For a number of years around the change over from 6-volt to 12-volt systems many manufacturers continued to use 6-volt coils with external resistors, or resistor wires, on 12-volt systems. Unhook the primary wires from the coil and check the ohm reading across the primary terminals of the coil. 3 to 4 ohms it is a coil designed and internally wound to use on 12-volts and does not need an external resistor. Ohms in the 1.5 ohms is a coil wound for 6-volts and needs an external resistor for use on a 12-volt system.

Thank you very much. Appreciate your quick and informative response. Will check that first thing this morning.

 

[Duner Wi]

My IH350U 12 volt has an additional wire from starter solenoid bypassing the resistor at the coil. This supplies 12 volts during cranking and aids starting under certain conditions. This is something Delco did when switching to 12 volts in the 1950s so it was not just an IH thing. My guess is if your solenoid you are using has 2 small terminals you could wire your tractor up with resister and jump wire to coil bypassing the resister while starting.

 

[tom upton]

My IH350U 12 volt has an additional wire from starter solenoid bypassing the resistor at the coil. This supplies 12 volts during cranking and aids starting under certain conditions. This is something Delco did when switching to 12 volts in the 1950s so it was not just an IH thing. My guess is if your solenoid you are using has 2 small terminals you could wire your tractor up with resister and jump wire to coil bypassing the resister while starting.

Just 1 small terminal on starter. Its a gear reduction unit. So this morning I checked resistance across coil sure enough 1.6 ohms. So I go to town and get another coil that says right on it "no external resistor required". Put it in and ran fine for the 20 minutes I ran it to break cam in. Went to restart and no go?? Put old 1.6 ohm coil back on and it fired right up?? I am now wondering if I had burnt the points bad enough that the new 3 ohm coil doesnt work with the slightly burnt points? I cleaned up points but will still only run with the 1.6 ohm coil. Is it worth trying a new set of points with the 3 ohm coil? Means another trip to town. Another question is how much run time should a good set of points tolerate with the 1.6 coil? I am only tractor pulling with this 88 so its not like its going to get a lot of hours. Am I thinking wrong here?

 

[Jim.ME]

Is the wiring all new or are you reusing part of the original harness. If reusing old harness, check the resistance of the wire from the switch to the coil. See if it has a section of resistor wire in it.

 

[Duner Wi]

I would check your new 3.0 ohm on another vehicle. If your points don't work with 3.0 but works with 1.6 ohm coil I can't see how it could be a points problem. Short story I have run coil that required resistor on 12 volts for long time . I did not have a resistor. Points may have suffered but diaster was not immediate.

 

[scootergmc]

Is the wiring all new or are you reusing part of the original harness. If reusing old harness, check the resistance of the wire from the switch to the coil. See if it has a section of resistor wire in it.

I agree. It should have a diode in it somewhere.

 

[tom upton]

Is the wiring all new or are you reusing part of the original harness. If reusing old harness, check the resistance of the wire from the switch to the coil. See if it has a section of resistor wire in it.

All new wiring. I wired as per the diagram for 1850 apart from starter. I just used the original push button for starter and jumpered from the main lead to the little post on solenoid. The diagram only shows 1 small wire connected to the field terminal on alternator to field on regulator. Then from regulator #3 post to ignition. I am now wondering if because I have the wiring seperate to starter do I need to connect the R terminal on alternator to #2 terminal on regulator, then #4 terminal on regulator to ignition? If I do this where does #3 terminal on regulator go???

 

[tom upton]

Forgot to mention in above post I am getting alternator voltage 14 plus volts to coil .

 

[Jim.ME]

You need to wire the Delco 10DN alternator and external regular as they are designed. Attached is a drawing of the alternator and regulator wiring with an ammeter (guessing you have an ammeter, not an indicator light). It is not the same as a newer Delco type 10SI with the internal regulator. By this drawing the regulator #2 goes to the ignition switch, #3 goes to the ammeter (battery source).

It is not uncommon for a 12-volt charging system to be in the 14-volt range.

 

[scootergmc]

If you bought an 1850 harness, this is the factory wiring diagram for the 1850 gas (eliminating any IT mistakes):

http://www.partsforolivers.com/1850_gas.pdf

 

[Jim.ME]

The wiring diagram scootergmc posted shows the original harness had a 2.0-to-2.4-ohm resistor wire spliced to the white wire inside the harness. That tells me they originally used a 6-volt coil. If you used all new wiring, you did not add a resistor wire or a ballast resistor, did you? If you came direct from the ignition terminal of the switch to the coil, you should be good to run a 12-volt coil that does not require an external resistor. The wire from the starter solenoid to the coil, that bypassed the resistor wire for starting, would be eliminated by using a true 12-volt coil as there is already 12-volts at the coil.

The 1850 originally used the Delco 10DN series alternator and external regulator as shown in the diagram.

 

[tom upton]

The wiring diagram scootergmc posted shows the original harness had a 2.0-to-2.4-ohm resistor wire spliced to the white wire inside the harness. That tells me they originally used a 6-volt coil. If you used all new wiring, you did not add a resistor wire or a ballast resistor, did you? If you came direct from the ignition terminal of the switch to the coil, you should be good to run a 12-volt coil that does not require an external resistor. The wire from the starter solenoid to the coil, that bypassed the resistor wire for starting, would be eliminated by using a true 12-volt coil as there is already 12-volts at the coil.

The 1850 originally used the Delco 10DN series alternator and external regulator as shown in the diagram.

So with a 12 volt coil is it o/k to have 14 volts going to it or do I somehow need to limit it to 12?

 

[Jim.ME]

So with a 12 volt coil is it o/k to have 14 volts going to it or do I somehow need to limit it to 12?

Yes, 14 volts is alright. Some charging systems will go even higher. !2 volts will not fully charge a battery. It is called a 12-volt system as that is the battery type, just like 6-volt or 24-volt

 

[tom upton]

Yes, 14 volts is alright. Some charging systems will go even higher. !2 volts will not fully charge a battery. It is called a 12-volt system as that is the battery type, just like 6-volt or 24-volt

Thanks. I thought voltage to coil had to be limited to 12 or lower so I put a resistor before the new 12 volt coil. It works but does not start very fast. I will remove resistor. Thanks again.