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just on with converting my 51 to 12v.what type of coil should i use,a ballest resisted one or not?the engine is stock.thanks

jon boy jonny,

If you use the ballast resistor, you need some method to bypass it during START. If you have a solenoid type starter, it should have a 'R' terminal on it so all is well. You probably have a foot starter so the starter switch must have a bypass terminal on it to power the coil with full oink during START...you probably don't have this type switch, so that would have to be purchased.

If you go with the internally resisted coil, you don't have to buy the resistor, you don't have to buy the starter switch, but you only get reduced voltage during starts (and the rest of the time too). This is probably fine. If the small difference between full oink and reduced oink causes the truck to start hard, you need to look at other things.

It's almost a 'six of one, half a dozen of the other' kind of deal.

I just noticed your location. Availability might have a hand in your decision too...huh!

Stuart

I'll take six. I can't eat a half dozen.

thanks for that.it looks like i can only get a external resisted coil,so will go that rout.if it dose suffer bad starting then i will have to look at bypassing the resister on start up.should i place a voltage reducer in the wire from the coil to the points?
cheers jonathan

jon boy jonny,

No voltage reducer needed! Have you taken a peek at your starter switch...the switch on the starter! If it has a small terminal hanging on the side, your bypass problems are over.

Stuart

sadly there is no other terminal on the starter so if i do suffer from bad starting i am going to have to get creative!do only 12v starters have the extra terminal.
jonathan

Us 6 volt guys dont have to much trouble with hard starting so I wouldnt be to concerned unless it really starts to give you grief. Good luck!

Jeff

jon boy jonny,

Using a internally resisted coil is certainly not the kiss of death. Wire it that way and give it a go...you probably won't even know the difference. The terminal is associated with the switch, which is a separate item that is attached to the starter proper to complete the assembly.

You can buy the switch with bypass terminal and put it on your existing starter. If doesn't know voltage from Adam. I am assuming you are going to keep your same 6 volt starter and run it on 12 volts...this is fine and should be plenty durable.

Stuart

My truck presently has the externally resisted 12v coil and it does not have the by-pass switch on the 6v starter. My truck usually starts on the first crank. I live in south Florida but your weather isn't that extreme so you might be ok with the same setup. The by-pass switch is nice and I'll probably wire one into the circuit down the road. You can always pretend you have Lucas ignition and that hard starting is normal Just kiddin', jon boy jonny.

LAROKE,

Did you mean to say 'internally resisted' coil?

Stuart

No. Sorry, let me clarify. I have a ballast resistor (and my coil has "must be used with a ballast resistor or resistor wire" printed on it)

Here's a link to my ignition/starting/charging circuits as currently wired (pdf file format)

Partial BillyBob wiring diagram

laroke.whats the red wire from the starter to the risitor?

LAROKE,

Your wiring is under construction...right! The BATT wire to the key switch isn't shown yet, hence the 'partial' in your link.

Stuart

no, wiring complete!the ballast resister goes inline in the wire from ameter to the + on the coil?whats wrong with lucas ignition?works fine in my 82 austin mini.not.in fact the distributer is still in orbit.

No way should a wire from the ammeter go to the coil, via resistor or any other way.

my mistake!it goes in the wire from ignition switch to + on the coil?

Red wire goes from starter to ammeter

Blue wire goes from ignition switch to ballast resistor

Black wire goes from ballast resistor to coil +

(you can zoom in on the diagram with the "magifying glass" tool and pan with the "hand" tool in the pdf viewer in your browser)

It's a partial diagram for clarity. Here's the full diagram of the truck's present wiring

current Billybob wiring diagram

Except that the original type turn signal director isn't wroking correctly, so, I have an aftermarket strap-on director in place and here is that sub-diagram.

After-market turn signal director diagram

OOPs! I almost forgot. Lucas = Lord of Darkness

thanks friends.i think i have got it now!all help is much appreciated.

Quick and easy... I needed a 12v coil to use on my 48 when I first got it and the first one I grabbed out of my box-o-coils was one out of a Rover 2000TC (P6) and it worked just fine..... I figure you should be able to grab a standard Lucas coil off a dead P6 around there at a breakers yard........

Remember though..... Lucas... the Prince of Darkness.... ie get to work early? and home before dark......