6 volt positive ground question

Which side of the coil should be connected to the distributor? I am not very familiar with this stuff...Makes it hard to trouble shoot 40 year old wiring problems..I have no lights, gauges don't move or flick when key turned on.. The starter does turn over the motor but I have no spark..Could it be voltage regulator or ???I will try anything...(well almost)..Thanks, EVILT

 

Nice truck. + side of the coil goes to the points. On an old Mopar, everything but the starter current p***es through the ammeter. A loose connection at the ammeter will kill everything including spark and lights.

 

On my ex's 53 flathead f100, there was 4 posts on the solenoid. Two for the bat cables, one for the "switch" and one was a power take-off for the whole truck. If there is a problem with that power take-off, it may be your problem...

 

The minus side of the coil ALWAYS goes to the points! Find a copy of a positive groung wiring diagram to prove it to yourself.

 

Oh man..No I am confused... I have been told positive side and negative side goes to the coil.. Anyone else?.. I will check the ammeter for power there...I haven't been able to find a wiring diagram yet...EVILT

 

Don't go on just what info being told to you.
You need to set down for a weekend and study how these car circuits relate and work. Go to the car manual and schematic site and pull any old 6 volt pos ground system and go to work.

http://www.oldcarmanual.com/
I believe Mac has some on his site too!
http://www.vanpeltsales.com/FH_web/flathead_home.htm

 

Nope. Positive to the points. This is a Mopar pos ground. That's what my Mopar shop manual shows. Check with the guys on the P15-D24 forum, that's what they run.

 

Pos to points--the points are the ground side of the coil circuit.

 

positive goes to the coil on a positive ground car like a Model A, 9n,2n, 8n Ford tractor, or anything Ford up to the 12 volt days.

Negative goes to the coil on a negative ground car.

 

I feel I should restate myself...this is to the point side of the dizzy.....remember that negative connects to positive, and we're dealing with a positive ground....so out of the harness side it's a negative charge.

Ever read Randy Rundel's book on automotive electricity?...great reading...

 

You'll know if you've got it back ***wards if you see your points going to burned in no time at all....

 

Been many a year, but I remember that if the battery on a generator system is totally discharged that it can reverse polarity, perhaps someone more knowledgeable can explain. I remember my grandpa shorting out the poles at the generator to get it to reverse back. Anyone know about this?

 

Yes. it's known as 'polorizing the charging circut'. Generators put out DC current,with a positive side,and a negitive side. Alternators put out alternating current,switching positive,and negitive current,many times a second Diodes, act as a one-way valve,separating the poles. 'Sparky'

 

Jalpy 43, Wouldn't an ammeter show a discharge if you had a fully charged battery and the polarity were reversed?

 

This thread shows that everyone who works on cars should have a basic electrical understanding, nothing special, just ohms law and how to use a volt/ohmeter would do. I think that would be like knowing how to use a torque wrench. It shouldn't be that intimidating but to many it is.....to bad. As was previously stated, an evening with a wiring diagram of the car and some basic knowledge would do the trick....

 

It depends on how the connections on the coil are marked. Does one of the posts say "ignition"? If so, the power from the ignition switch goes there, that's the primary side of the coil. The other goes to the distributor, which is ground, when the points close. If it's a generic coil and has + and - posts,
then the + post is the primary side of the coil winding, power goes to it.

 

OK, Here we go..I am in no way intimidated by this. I have a background in electrical engineering...This truck has been molested for who knows how long and has been parked for 40 years.. I am trying to get a little insight into what may be going wrong or hooked up wrong without having to start wiring the whole truck right now...OHM's law..BLAH BLAH Voltage in must equal voltage out....heard it for the last couple years...Yes I know that electrons actually flow from Neg to Pos. not the other way around...That doesn't do me a whole lot of good when half the wires are the same color, spliced, multiple times..Grounds are dirty...etc...If you don't have any positive input...Start your own Damn post about Basic electrical theory...Half of the wire schematics I find for this vehicle online are so poorly scanned you can't read all the details...The only thing missing now is spark.. I have headlights, blinkers, dash lights, horn.....Sorry for the rant...EVILT

 

Just to reiterate, on a Mopar positive ground system, the coil + goes to the distributer. I just verified this on my '55 Ply.

 

If you have no spark but the starter is spinning OK, why not try a jumper wire from the battery neg post to the coil neg post, then crank her over? That should byp*** the wiring under the dash. Also, the old Mopar distributors have a habit of grounding the point wire at the distrib backing plate/housing. Make sure that hasn't happened.

The P15-D24 forum has a link to the pilothouse forum. Nothing but Mopar flathead 6 fans on both boards. PM me if I can help.

 

I have power from my switch to my coil and from the coil to the distributor.. I still have no spark..Should I see a spark on the points with the cap off on a pos. ground system.. I have none...points look good..condensor looks good, cap and rotor and wires..so-so..I should have all new tune up parts in the morning.. I still think it is weird though I have no spark at all...not even weak one..Normspeed I will check out the wire you are talking about...Thanks,EVILT

 

Yes. The ammeter needle would be reversed. I know on my shoebox,when I changed to 12v neg. ground, I had to run the ammeter wire,the oppsite way through the loop, on the back of the gauge. Sparky

 

Correct. Now let's ***ume the coil has been replaced with a coil marked to be used in a negative ground system, like a gm product. The power lead coming from the battery or ignition switch would go to the PRIMARY side of the coil, which would be the + terminal, and the wire going to the points would come off the - terminal(secondar winding/ground side of the circuit) on the coil.

The points are always the ground side of the circuit, whether the system is positive or negative ground.

 

EvilT can I use the "It was really early and I was stupid" excuse? What I should have said was the points are ALWAYS on the ground side. Sorry, hope I didn't confuse you worse.

 

OK, the coil that was on the truck has a bottom post and a top post next to the coil tower...The replacement coil has both posts on top..I don't see that either are marked for positive ground... It just says 6v on both of them..Is there some sort of code on em? Thanks, EVILT

 

No problem, I probably deserved it. After I posted, it seemed I was flaming you, sorry. What I was trying to say is that IN GENERAL, lots of mechanics shy away from learning the basics about electricity and get intimidated. I fully agree with you about not being excited about working on old cars where all the wires are the same color with 50 plus years of PO splices, cuts, black tape, jumpers, etc. I hear ya. Good luck in your endeavors.

I just realized something, correct me if I am wrong. Regardless of the markings on a coil. A coil is a coil, i.e. it's an inductor and inductors are primarily used non-directioally. So the polarity as marked really shouldn't make any difference, one side is high, the other side is grounded, regardless if the high is +6volts or -6volts, as long as the other side is grounded. Isn't that right???

 

Start by not Kirchoff'ing Ohm's law.

Polarity of the DC only matters to motors......

 

My two cents...I just bought a 1955 Dodge Custom Royal Lancer...6 Volts and Pos ground. I replaced the coil...The side which has the + marked on it...is connected to the DIST. I have been driving this car to work every day...It runs perfectly.

Now when I took the old coil out...it was wired with the - to the dist...The car still ran. So...I am pretty sure that it can be done both ways; however, I believe the correct way with a POS ground system is to put the + terminal to the dist as the grounded circut dictates.

Tim
MBL

 

Went looking for do***entation on this last night--Ford library no good, here, as early flathead coils are impossible to install wrong (some here will see that as a challenge...) and late ones are marked distributor/switch or some such. Did find a Holley built '42-48 with the distrib terminal marked positive too...
The polarity could of course be figured out somewhere in the endless ****ysis meter sections of the manuals, but I didn't have enough coffee to go there.
Echlin finally produced the needed flat statement: Coils on pos ground mount with pos terminal to points, and vice versa. It did note, with resignation, that Ford coils are marked distrib/switch...and gave as a tech hint that clear polarity marks was one of the reasons you should switch to an Echlin coil.
Echlin/NAPA electrical manuals from '52 and '55...great reading.
Along the way, I ran into different estimates running from maybe 20%-40% loss of efficiency in a coil wired backwards, along with explanations that hurt my head. Anybody here know how to build a "hot tube" ignition or something else that doesn't require this electrical ****??

 

OLDSGUY, no problem..I was a little frustrated when I replied...I have tried coil both ways and also a new coil both ways. still no spark.. I do have power from the coil to the distributor(screw on outside of body)..then there is a little jumper to the points....There is also a condensor in the dist. that connects to the points... I see no other wires.....The little jumper did have a nick in it from getting pinched between the cap and base. I am gonna go after it again today....There is no better way to learn about your new car than to troubleshoot everything on it....Brakes are next...wish me luck...EVILT

 

This just happened to a buddy's car - not that it matters but it was a '49 plymouth business coupe -6 volt - positive ground. Died on the way to meet up with us - meaning everything WAS working.

We first checked the points, cap, etc. - we DID have power to the coil - yet the distributor would not fire. We checked the distributor - points , condensor - the internal wires - everything - yet NADA.

After some head scratching we tracked it down to a FAULTY BREAKER plate connection. The factory breaker plate is mounted to the distributor body via a small "L" bracket. The breaker plate is SCREWED to the "L" bracket but then the "L" bracket is riveted to the distributor housing. The rivets after 55 odd years lost their connection to the distributor.

I suggest you verify the distributor is functional. just a thought.