Cranks but won't start. Unplug ground at field spade on Alternator and it starts?

-
67Dart273 said:
It would be better to replace those terminals. Some of the supply sources have changed/ dried up so you will have to search. "Packard 56" and various. Be CAREFUL that the terminal has the tension area wrapped around the sides as exactly in your photo. There are some different ones that bend over the top and they will not fit some Mopar connector shells

I know Mattox has done some posts on this.

The other thing is, if you get this finally settled down, working, but still have some voltage drop in the IGN1 "run" circuit, that will cause overcharging as the VR sense will be low

One way around that is to electrically break the "run" IGN1 coming out into the bay, use the end from the switch to fire a relay, and supply the relay contact power from say, the starter relay big stud, and then put all the underhood "run" loads on the switched contact.
Click to expand...
After cleaning firewall terminals, only red female battery terminal was removed and wire brushed, car started even though battery had not been on charger for two days at 12.7 volts. Haven't checked Ign 2 volt drop yet but seems to consistently start without putting battery on charger. Drove car around for 40 minutes Anp Meter stable slight charge but needle on white middle mark. After drive battery was 15.2 volts engine running before I shut engine off. Alternator stud is 15.4 volts and if I unplug VR it goes down to battery voltage.

With ballast and Unilite unplugged I got .9 volt drop at Ign 1 at the VR. So I have to go work on that bad connection issue now. Until I can find fix the voltage drop problems car isn't fixed even though it starts and runs now.
 
Some progress: I see .06 volt drop to + side of coil while cranking engine. Also see 11.5 volts at coil when cranking same as battery. This was with ballast resistor unplugged.

With ballast resistor plugged in but Unilite unplugged I get .35 voltage drop to coil. In this test current flows through ballast and 3.5 amps flows through field circuit to alternator. So it puts a bit more load on the circuit but seems to be able to flow current correctly with only .35 volt drop to coil.
 
Last edited:
The thing is, sometimes these are "self repairing" (maybe temporarily) just by wiggling, disconnecting (examining) and reconnecting corroded terminals.

Once again, what I could SEE in your photo indicates corrosion, and the two most important terminals IN THE ENTIRE HARNESS are the big red and the big black ammeter circuit terminals. I would replace them

Ain't 50-60 year old wiring fun?

My 67 when I got it had bone stock wiring, and there was a 1.5 or more volt drop in the ammeter/ ignition circuit, so the battery was running 15.5 and more
 
67Dart273 said:
Once again, what I could SEE in your photo indicates corrosion, and the two most important terminals IN THE ENTIRE HARNESS are the big red and the big black ammeter circuit terminals. I would replace them
Click to expand...
I have the correct terminals on hand.

PXL_20240712_175530119.jpg
 
Not seeing any corrosion on ignition switch terminals. Hooking power and Ign 1 together does not improve voltage drop in engine compartment.

Disconnected starter relay battery terminal, ran jumper over to alternator battery wire, saw .2 less voltage drop so minor improvement sending battery voltage in that way

PXL_20240712_183212564.MP.jpg
 
Progress however slight. Don't forget that drop (and it can come and go) can be right in the contacts of any switch. Part of why relays are useful
 
67Dart273 said:
Progress however slight. Don't forget that drop (and it can come and go) can be right in the contacts of any switch. Part of why relays are useful
Click to expand...
I been reading up on relay mod. Its much more precise if VR gets its voltage straight from battery via relay vs a maze of connections/switches/hops.

Prior to me cleaning all the connections I measured .4 volt drop between VR Ign 2 wire and battery when engine was running. Even if every connection is perfect there will always be some drop because of the many hops connections maze the current has to travel with the original circuits.
 
If nothing`s getting hot and if it`s starting and running fine, I wouldn`t sweat it even if the charging system is putting out 15 volts.
You're going to drive yourself nuts with all this testing.
 
.4 is not bad. Not bad at all. I would recheck the charging/ running V to be sure but I'd say you are OK with that.
 
I still get a crank no start some times. But I don't think its the cars wiring.

If I jump a wire from + battery to Ign 1 at ballast resistor connector (key off) OR put key in Run I got the following:

Ign 1 at VR: 1.3 volt drop
Ign 1 at VR, Unilite unplugged, .8 volt drop

If I run wire from + battery to VR with Ign 1 disconnected I get .19 volt drop.

So if I get same voltage drop jumping battery straight to Ign 1 key off by passing ALL wiring in the car it seems like excessive drain at VR. Also the pin I push into Ign 1 connector is hot when I remove it indicating excessive current

I measure 4.6 amps between Ign 1 and VR and 4.8 amps across field circuit. Was 3.4 amps a week or so ago.
 
Last edited:
The difference in field current could be brushes, and normal. If you look the field current test, in the alternator section of section 8, it shows hand rotating the alternator while measuring field current. This is because the brushes do not make all the great contact, stationary, and when rotating / running, sort of "average it out."
 
It won't start at all anymore. Got 11 volts at coil cranking and 10 volts going to Unilite while starting with key everything hooked up. Took dist cap off and looks like distributor cap burned up? Distributor cap replaced few weeks back?

PXL_20240713_163034816.jpg
 
I don't know anything about unilites but I would be tempted to swap it out just to change the problem. Either just slap a breaker points dist in there, or find a Mopar stock breakerless dist and look up the HEI module conversion. It is not very hard.
 
From what I read searching internet is when cap melts in middle could be gap between cap center and rotor or center button broke off. Center button in cap some times breaks off if cap not installed carefully.

Weeks back I ordered cap and rotor and rotor was wrong so only replaced cap. Was cap a mis match for old rotor?

But hey all this cleaning electrical connections ect I have 11 volts at coil when I crank it over. So effort not a total flop right??
 
67Dart273 said:
I don't know anything about unilites but I would be tempted to swap it out just to change the problem. Either just slap a breaker points dist in there, or find a Mopar stock breakerless dist and look up the HEI module conversion. It is not very hard.
Click to expand...
Unilite module is no spark and doesn't draw any current any more. Cap rotor toast. So even though Unilite ran fine for 15 years trouble free do I replace module/cap/rotor or switch to something else?

I will say this: seen many used Unilite distributors for sale on this site and have not seen any of them sell. So if I go with something else its has zero resale value from what I see no one wants them ...
 
340sFastback said:
. Drove car around for 40 minutes Anp Meter stable slight charge but needle on white middle mark. After drive battery was 15.2 volts engine running before I shut engine off. Alternator stud is 15.4 volts and if I unplug VR it goes down to battery voltage.
Click to expand...
That all makes sense, right?
The alternator is the power supply that runs at higher voltage. Without the magnetic field power, the alternator doesn't generate anything and the battery takes over as the power supply.

15.2 to 15.4 indicates there is some slight resistance between the alternator and battery, and probably significant difference between the alternator and regulator.

340sFastback said:
I measure 4.6 amps between Ign 1 and VR and 4.8 amps across field circuit. Was 3.4 amps a week or so ago.
Click to expand...

340sFastback said:
If I jump a wire from + battery to Ign 1 at ballast resistor connector (key off) OR put key in Run I got the following:

Ign 1 at VR: 1.3 volt drop
Ign 1 at VR, Unilite unplugged, .8 volt drop
Click to expand...
The difference here is current. With the Unilite plugged in, more electrons are trying to get past the resistance. Since the power is coming from the car's battery the increased current with the Unilite plugged will be indicated. it should take quite a bit more current to cause a .5 V increase in votlage drop.

Lets put the information you collected onto the drawing.

Engine running, battery recharged.
1720960438630.png

Voltage is high causing an overcharge situation.
Voltage at the regulator's Ign input is probably 14 to 14.9 Volts.
The alternator is supplying a minumum of 7 amps.
So we can conclude that the R6 connector at firewall is not the primary source of resistance.

Now the other test, engine off, key in run.
1720961482576.png

With the Unlilte connected there is 1.3 V lost between the battery and the ballast resistor.
Field current has been measured previously with engine running. It will be a little less when supplied with 12 Volt power.
Current through coil is probably around 2.5 amps with ignition on.
Unilite draw is unknown but significant.
Therefore
There is probably significant resistance between the feed to the key switch and the connection at the ballast resistor.
It is probably before the connection at the regulator because the alternator is supplying at over 15 Volts even at relatively low loads.

Hope that helps.
 
67Dart273 said:
I don't know anything about unilites but I would be tempted to swap it out just to change the problem. Either just slap a breaker points dist in there, or find a Mopar stock breakerless dist and look up the HEI module conversion. It is not very hard.
Click to expand...
The rotor for my Unilite 47 series distributor, MAL-322, is discontinued. Was hoping to put a Pertronix conversion kit, they have one specifically for Unilites, but without a rotor that distributor is now a paper weight.

Local parts store say they can have this single point unit in today. So I can throw that in and put a Pertronix kit into it later or just keep it around as a spare.

Distributor Single Point.jpg
 
Put single point distributor in. Timing seems to jump around 3-5 degrees both at idle and when rev'd. But shaft and advance don't have any slack and move freely? Also broke up stumbled on drive with MSD coil swapped in auto parts coil better but still seems like hick up every once in a while and same timing jump around issue. But car seems to run pretty good. Starts very quickly easily.

Saw 14.75 volts at battery after 30 minute drive. And voltage drop between battery and Ign 1 at VR is .2 volts.

I think cars electrical very healthy now. But single points timing jumping around not good. Point gap set to .015 inch. Have a Pertronix Igniter 1 kit coming.

I did a lot of leave key in Run engine off during voltage drop tests and other previous testing. So some of ignition failure could be user error induced.
 
Took single point distributor out, move vacuum advance plate around to make sure its seated, opened up point gap (by eye), now ignition seems to be working right. If I rev hold RPMs up to bottom out mechanical advance (around 12 degrees slots welded short) timing is rock steady does not move. Seems to bounce around 1-2 degrees or so idle lower RPMs.
 
You must log in or register to reply here.
-

Back
Top