6 volt starting problems

I have a model A ford and it is still 6v.  However, I use a 12 v battery so it will start easily.  I think that your coil is not getting enough voltage to excite the secondary field, which fires the spark plugs.  The starter fields are wound heavier in a 6v starter because of the amperage, so using a 12v battery reduces the amperage and spins the motor faster.  You will need to add a voltage reducer resistor in the coil primary to drop the voltage to 6v on the coil...available at NAPA.
The old remedy was to install an 8v battery in the 6v system, but I dont know if they are still available. 
Good luck

It's been a while, so I'm not sure what coil I have, but seems I got a new one when I went thru the distributor. I'm not gonna switch to 12 volts because I have a good working generator and all new wiring with a cut out and proper light switch.
 These things worked fine for decades on 6 volts, if well maintained. I just have to figure out where the real problem is.

Wallyworld battery kiosk starter cables are way to small for 6 volts. Every connection in the starter circuit, battery, frame, starter mounts, hot cable battery to starter switch, contacts in the start switch, and connection from start switch to the battery post on the starter are critical. Failure of any one to carry 300 amps without serious voltage drop can keep the engine from cranking well. 6 volt battery cables ought to be 0 or bigger, not 4 gauge.

My gas 4020 uses a 6 volt coil on a 12 volt battery, but with a resistor. A special contact on the starter solenoid supplies full battery voltage to the coil while cranking. Seems to work well. It would take a separate relay on your tractor and a three volt coil with external series resistor to emulate the circuit at 6 volts. Is the coil polarity the same as the battery polarity? Wrong polarity on a coil will get some spark but not as effective a spark as proper polarity.

It would help ignition while cranking to connect the ignition switch to the cable near the battery post rather than at the starter switch.

The ground wire connection to the frame needs to have a full bare area, not just the bolt, but all the connecting surface bare on the wire lug and the frame. Ditto for the starter mounts and the battery box mounting if the ground goes to it.

On a 6 volt system my experience dating back to 1955 is that battery posts and connectors need to be cleaned twice a year because there's not enough voltage to tolerate voltage drops.

5.5 volts at the battery isn't too unusual while cranking. A better test is to check the voltage at the starter, ideally it will be at least 5 volts. Cleaning connections and using large sized conductors is what it takes to keep from loosing voltage at the starter.

Gerald J.

Tuck,
Sounds to me like one of two things. Either the Battery has a cell starting to go away in it, or the starter is pulling more amperage than neccessary "stealing" power from the ignition circuit. A draw test will determine the Battery. In most cases, where you have a senario as like with your situation, the power source at the Battery itself is not supplying enough power under load especially a 6V Battery which only has three cells. If the Battery passes the draw test, you might have an internal problem with the Starter motor. When you hand crank it, the Starter is not engaged and not drawing on the system. There's plenty of standing voltage in the Battery, (no draw from the Starter) and it fires right off. As for the cables, 1 gauge is the norm. Anything larger works fine also. That's a case where bigger sometimes works out to be better. I have 1 gauge cables on my B which is still 6V and the ole' girl fires up all the time with a full Battery. The Battery is always on a tender to keep it active. Cuts down on the sulfating problem that 6V Batteries have when they sit for long periods of time without being used.... HTH
Steve@B&B

You're probably losing another .5 volts or more through your battery cables. You might be able to avoid some of that if you use extra heavy cables. Taking the ignition wire directly from the battery post would avoid that too. An AGM battery would drop less voltage, but they are pricey and I imagine a 6 volt job would be hard to find.

Edited by DougS - 16 Aug 2017 at 8:29am

When you get it going, check the timing.

There is voltage at the coil, or it wouldn't start when I let off the starter switch. Evidently, it's not getting enough while the starter is cranking it  over.
 Timing is right to my ear and she backfires twice when you throttle down from WOT after warming up.

hmm. this....
There is voltage at the coil, or it wouldn't start when I let off the starter switch
.....
Please check to be sure there IS voltage on the coil WHEN starting !

I've had riders and one of my D-14s where the ignition switch was wrong or faulty so it'd turn over with no power to coil;let go, key goes to 'run' and engine would start and run. Luck of the draw the engine was spinnng just fast enough and the plugs fired at the right time.

Also, if you haven't done so , replace 100% of the wiring. Get a 'kit' from Steve or make your own. One way or the other, you NEED to be SURE the wiring is correct.

Jay
 

jaybmiller wrote: hmm. this.... There is voltage at the coil, or it wouldn't start when I let off the starter switch ..... Please check to be sure there IS voltage on the coil WHEN starting ! I've had riders and one of my D-14s where the ignition switch was wrong or faulty so it'd turn over with no power to coil;let go, key goes to 'run' and engine would start and run. Luck of the draw the engine was spinnng just fast enough and the plugs fired at the right time. Also, if you haven't done so , replace 100% of the wiring. Get a 'kit' from Steve or make your own. One way or the other, you NEED to be SURE the wiring is correct. Jay   There is voltage at the coil, or it wouldn't start when I let off the starter switch

The ignition switch is a push pull (on off) switch on the electrical box and puts battery voltage directly to the coil.
ALL wiring is 100% new and everything works, cept one headlight has a ground problem internally, but works most of the time.

That's what I plan to do Butch. The coil was new, from Farm and Fleet, that's enough to draw suspicion right there I plan on taking the digital meter over and check primary windings too.