starts AFTER cranking

I recently bought a 300 u ,,, it has been converted over from 6 to 12 v.

I think the conversion wasn't executed particularly well.

It seems to me that the engine cranks, but doesn't fire until I let go of the key and quit cranking... but then it fires and starts pretty much every time.

Would there be a legitimate reason why this would be happening.? I'm pretty sure it is happening. I think it would not fire as long as I kept cranking.

The thing seems to start pretty reliably, although it hasn't been too cold yet, but I'm wondering why it is like this... and maybe it won't go so well once it IS cold.

you have a weak ballast resistor and/or no hot wire from the starter to the coil which provides a full 12 volts to the coil when cranking

Very common, especially is cars and trucks from the 60s-70s.

Two possible causes.

#1 - keep in mind that when you are actually cranking, system voltage can drop to 9 volts - and some coils don't work at 9 volts. The instant you stop cranking - voltage spikes up to 12 volts and it fires. This is why it is best to have a 6 volt coil in a 12 volt system. Most do. 90% of all cars and trucks that came new with 12 volt systems use 6 volt coils. Same goes for many tractors.

#2 - as already mentioned - you might have a resistor bypasss or resistor problem - if you have one installed.

Need more specifics on exactly what you have. 6 volt of 12 volt coil??

You need to by-pass the resistor while cranking so maximun voltage can reach the coil. The old Ford fender mounted starter solenoids had a second primary terminal just for that purpose. Delco starters had one also but it was mounted directly on the starter.

Real, my answer has to be IT DEPENDS:

Id say the coil voltage is too low due to excess voltage drop while cranking, and that could even be a weak battery problem. Have the battery LOAD TESTED to see how much its voltage drops under a heavy load.

Another cause of excess voltage drop might be a bad starter thats drawing too much current!!!

Another cause may be a bad cable or connection, Id remove, clean n wire brush n reattach each n every battery n starter n ground n switch/solenoid connection then try it (after battery has also been load tested)

Another problem may be a bad (resistive) ignition switch. Try hot wiring her, see below


NOW if none above are the causes, lets explore further:

1) If????? you have a 6 volt coil and an external series voltage dropping (12 to 6) ballast resistor PLUS some sort of ballast by pass that supplies unballasted battery voltage to the coil ONLY WHILE CRANKING, Id say that switch or its wiring or connection has failed. If its working, ONLY while cranking the ballast is by passed around for a hotter starting spark. I owned those tractros years ago but didnt think they had any ballast by pass circuit or system so I doubt this is the answer !!!!

2) If its a 6 volt coil and an external series ballast (more likely then above) that has no ballast by pass system, perhaps the ballast is too high ohms to properly match the coil i.e. theres insufficient coil voltage ESPECIALLY WHILE CRANKING. If you turn on the ignition and the points are closed a volt meter on the coils input (NOT to distributor) terminal should read like 6 to 7 volts (if its a ballast system and 6 volt coil) but if it reads like 5, THE BALLAST IS TOO HIGH IN OHMS.

BOTTOM LINE I suspect is theres low voltage on the coil while cranking (bad battery or starter or connection) or else the ballast is bad (too high ohms) or else the ballast by pass isnt working (but not sure it even has that) or esle theres a high resistance bad ignition switch?? Maybe try hot wiring to the coil n see how she does then !!!!!!!!! If she starts okay then I suspect a faulty (resistive) ignition switch or some of its wiring or connections.

On that 12 volt tractor you need either a 12 volt coil or a 6 volt coil with the external series voltage dropping (12 to 6) ballast resistor YOU MAY HAVE THE WRONG COIL OR AN INCORRECT SIZED BALLAST

Theres more that may be wrong, but this is plenty to get you started, let us know what you find

John T

All the answers below have merit!
Here is the answer.
Go to your favorite Auto Parts store and purchase a Starter relay for a 62 Ford Galaxy. It will have four terminals on it. 2 big copper studs, and two smaller threaded terminals between them on the edge.
Mount this where the original is located on the starter. The big studs are usually not labeled. The small terminals will have an S near one, and and an I near the other. Connect the battery cable, and the fatter small wire to the big stud closest to the S small terminal. (this is where they were removed from on the old relay)
Connect the Starter motor conductor to the other big stud (it is often a copper metal strip making the connection, If you need a different one to make it fit it can be made from a flattened piece of 3/8 copper tube with appropriate holes)
Connect the starter button wire (Small existing wire from the dash) to the S terminal.

A new wire and terminal ends needs to be installed from the I (small terminal) to the coil side of the existing ignition resistor. This gives max battery voltage to the coil for starting only. When the relay is on, cranking the engine, the I terminal will be connected to battery volts. When the starter is off, that terminal is disconnected and the coil gets regular resistor volts for operation.
The reason for the second terminal is that it is necessary to make it separate from the starter big terminal to keep the ignition from trying to run the starter motor, which would melt wires.
Good luck, Jim

My 12v M was this way. I just always figured it to be because the engine was spinning over so fast, that it wouldn't fire until it slowed down a bit when letting off the key.

Many of the Delco Remy solenoids had a bypass terminlal, while cranking the bypass allowed full battery voltage to go to the coil Sometimes the wires gets off the terminal. Has this to happen on a Chevrolet truck. This would be the first thing to look at.

"because the engine was spinning over so fast, that it wouldn't fire until it slowed down a bit"

WOW! THAT'S a DOOZY!

Could hold true if it has a mag????

But the faster a Mag turns the more energy of a spark it creates !!!!!!! HOWEVER if the mag is spinning so fast its impulse assembly stops operating (as it should at typically a couple hundred RPM's) then she would want to kick back pretty bad because then shes firing at maybe 20 degrees BEFORE TDC. BUT thats a bit different symptom, if thats the case shes gonna buck n kick back (shes firing before TDC) as opposed to just not fire at all. This can happen (Mag ignitions) if converted to 12 volts but the 6 volt starter is retained, but its not that common and she sure acts differnt then versus she dont fire at all.

I thought we were talkin about a coil ignition system???

John T

(quoted from post at 08:41:57 12/11/10) My 12v M was this way. I just always figured it to be because the engine was spinning over so fast, that it wouldn't fire until it slowed down a bit when letting off the key.

Click to expand...

Nah, it's because the starter is sucking so much power off the battery, there's basically none left for the coil.

oh my god... I see electronics principles are completey out the window over here!!!!

the starter is sucking the battery so low that spark is weak.. as soon as you let off the starter, volts come up, engine is still spinning and thus starts.

this forum needs an electronics 101 course for christmas B-A-D-L-Y !!!

soundguy

Run a separate wire from your battery to your coil then see if the engine start's easier and keeps running. Just do this once Hal

My 300 Utility does the same thing. It always starts so I don't
worry about it. Mine has been converted to 12 Volts.

Ok, the so the coil is not getting enough juice. What do you do about it? In my case it's a 53 SH converted to 12v with a 12v coil with no resistor needed. I am wired directly from the battery + post to the stock push pull switch to the coil. What gauge wire do recommend for that circuit? How would you check to see what amperage the stock push pull switch is letting through? That is the only thing that is not new.

As I noted down below, if you have a 12 volt coil and NO external series voltage dropping (12 to 6) Ballast Resistor that you can by pass while cranking (to increase spark energy) theres less you can do. Thats the advantage of using a 6 volt coil and the ballast by pass while cranking, because when the battery voltage drops you can still apply plenty of voltage to the coil (via ballast by pass system) for improved starting..

SO WHAT CAN YOU DO, heres a few things

1) Use heavy oversized battery n starter n ground cables to reducde voltage drop while cranking.........

2) Use a good high CCA battery which doesnt drop as much voltage while cranking.

3) Use oversize wire (like 12 or 10 gauge) from the Ignition switch to the coil and coil to distributor. CHECK ALL CONNECTIONS

4) MAKE SURE THE IGNITION SWITCH ISNT FAULTY/RESISTIVE and all the wiring and connections in the LV ignition primary are good.

5) Make sure the starter isnt drawing excess current and dropping battery voltage to an excess

A clamp around ammeter can show the ignition primary current, typical would be around 4 amps. A voltmeter can measure voltage drop across an ign switch (ideally you dont want any) or an ohm meter can meassure the resistance through the closed switch (ideally very low NEAR 0 ohms)

An easy way is just to use a jumper wire to by pass the switch and hot wire the coil to see how she does then, that can eliminate any faulty/resistive switch contacts.

Turn her on and with the points closed measure the voltage on the battery,,,,,,the switches BAT INPUT,,,,,,,The votage on the switches IGN OUTPUT,,,,,,,the voltage getting to the coil,,,,,,, IDEALLY they should all be the same but when you start seeing drops, you have found the guilty component or connection or switch etc thats dropping voltage. THATS AN EASY TEST DO IT !!! Measure voltage at all those locations to find the voltage robber grrrrrrrrr

Got it????????????/

John T

Had that happen a couple three times on different stuff. Couple times it was bad grounds. Once it was a battery with a bad cell. Only made ten volts. They all cranked pretty well.

With respect, it is a multi-pane window, and not all the "pains" are broken. Some are just at the wrong end of the spinal column. Jim

and yet... truth is truth!

starter spinning too fast... that was a good one...

My tolerance for wrong thinking is so calloused up and numb from the small proportion of head strong experience free students in my general studies environmental classes that I have learned to be very very patient. Jim

i must admit.. i get a bit of an eye twitch when i see the casual message posted asking how to wire a headlmap up to a lamp switch.. etc... that's the kind of think that makes me wonder how the average person is able to function in society without some very basic understanding of how things work and interact. I don't expect the average joe to know alot about electronics. but I kinda think they should get the wire bat to switch to lamp to ground kinda thing..

I don't even hang out here. another buddy on another board sent me this link to check out... reminded me of all the stories about muffler bearings, vw bug water pumps and that sort of thing... was good for a chuckle. I'll move on now... i'm not here to ruffle feathers.. it just truly shocked me that that was some honest to god rational thinking and troubleshooting that hit upon the idea that the starter was too fast for the engine to start.....

soundguy

Excellant. Thank you!!

(quoted from post at 20:18:26 12/11/10) i must admit.. i get a bit of an eye twitch when i see the casual message posted asking how to wire a headlmap up to a lamp switch.. etc... that's the kind of think that makes me wonder how the average person is able to function in society without some very basic understanding of how things work and interact. I don't expect the average joe to know alot about electronics. but I kinda think they should get the wire bat to switch to lamp to ground kinda thing..

I don't even hang out here. another buddy on another board sent me this link to check out... reminded me of all the stories about muffler bearings, vw bug water pumps and that sort of thing... was good for a chuckle. I'll move on now... i'm not here to ruffle feathers.. it just truly shocked me that that was some honest to god rational thinking and troubleshooting that hit upon the idea that the starter was too fast for the engine to start.....

soundguy

Click to expand...

You're a legend in your own mind :wink: