1972 dart - stopped running while at 50 mph ? no warning

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67Dart273 said:
Let's try it this way. You may not have hot enough spark. Jumper power to the coil direct. By the way do NOT leave this connected any longer than necessary than to make the test. If the engine fires and runs, you can leave it connected for a minute or two. This is hard on the coil and points

Now with the jumper connected, crank the engine by using a screwdriver between the two bare terminals on the starter relay, the "big stud" and the "big square" terminal"

Now you can see the spark and see how good or how bad it really is.

I am "assuming" this because you say "no spark at plugs." The rotor, cap and wires do not look too bad. The only thing left in that mix is the coil wire. You can check it (and the other wires) with an ohmeter
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ok i did try to start it that way earlier , with a remote starter switch , no start . i will try the spark test again this way , another day .

yes i tested coil wire ... it is getting spark ........ next tested resistance of the coil to cap wire , but could not get a steady reading . it would just flash a number briefly before going back to 1 , but flashed anywhere from 565 to 998 . so i got the 74 valiant slant six started up , and after a short warming . took out its coil wire and put the darts in there . the valiant ran , seemingly just fine . i did not try the valiants coil wire in the dart , because i don't want that to get screwed up by whatevers going on with the dart . just paranoid probably , but not doing that . i checked the resistance of the ballast and got a reading of 1.7 and 1.8 , but , again , not sure what that is supposed to be .

i will test the other wires too . what should they read ? also shouldn't there be little sparks at the points when the engine is cranking ? there was not , they were opening and closing and i got a dwell reading . i am thinking something with the dist. maybe . rotor and cap and points are new or a few months old . wires and condenser are somewhat older .
 
George Jets said:
Come to think it, how many volts in your battery? Should be 12.5 volts min.
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good question , not sure ill check another time , working outside and done for today , but i have been cranking it for days now and it probably isn't good at this point . it was good before this though .
 
If you can read the dwell then your primary system is working, and your Timing Chain is at least, not broken..
During cranking, with a good-working condenser, you should not see any sparking; it is the purpose of the condenser to stifle that exact thing.
At this point you should be seeing a stream of sparks issuing from a near-grounded coil-wire, while cranking. With the primary ignition known to be working, and no spark at the coil, the coil is NFG on the secondary side. You can prove that with your ohmeter, but you will have to isolate it out of the circuit. The secondary side should measure around 80 to 100K-ohms, compared to the primary side being about 1.0 or less. This is not diffinitive. There is a proof test I can tell you about later if need be.
When you find your spark, you will probably have to get your ring-seal back, by squirting a lil oil into every cylinder.
 
Post #27. Melted the wire. The high current surge might have burned the points. Need to check.
 
"ok , so i tried to check the timing , with a remote starter switch , but could not get the timing light to flash much at all , one or two random flashes , and nothing . tried two different timing lights a few times each , same result or nothing . i feel like i am doing something wrong . so i could not find a solid core wire , so i used what i have . i tried to check spark at first with the remote starter . zero from coil or plug wire number 1 . then i re read what you said a few times ( i takes me awhile ) and tried with the key . from what i could see looked like an ok to good spark , had the gap at about 3/8" , from looking between the bottom of the hood and cowl and with sun in the mix . heard a zap zap sparky sounds too . tried the same thing by putting the wire with tester in the cap where number 1 goes . got nothing , no spark , no happy sounds . then pulled the cap , pressed the remote starter , rotor is spinning , points are opening and closing , but no sparky goodness from those either ."

If I am reading this correctly ^^^^, does this not mean that the ignition system is in fact working with high voltage coming from the coil tower? Sounds like it is not getting to where it needs to be.......

I would be looking at the components from the coil tower to the plugs, and of course the timing chain or loose distributor.

BTW.......With that shorting as @Bewy suggested, I'd be back checking to make sure nothing else got fried (check for coil tower output again).

Good Luck
 
Swap in another coil, yes after 50 years they do go bad.

You should be able to fire that coil by opening and closing the points with a plastic knife.

That way you are not sucking all the juice out of the ignition system with that old heavy wore out starter. It's a good test for the coil and shows the points and condenser are working properly.

Want to make sure that coil is firing good. Need a full charge On that battery too.

How many years old is that battery? They need to be replaced too as they lose their push over time.
 
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Did you index your rotor like I described?
Your ignition system could be 100% working correctly, but if the chain has jumped, it will be impossible to guess where your spark is going, other than to say it is not in the right place at the right time. The method I described only takes a couple of minutes and requires no tools.
If you have to move the distributor to align things, that guarantees something has changed inside the engine, and points straight to an out-of-phase cam.
 
AJ/FormS said:
Did you index your rotor like I described?
Your ignition system could be 100% working correctly, but if the chain has jumped, it will be impossible to guess where your spark is going, other than to say it is not in the right place at the right time. The method I described only takes a couple of minutes and requires no tools.
If you have to move the distributor to align things, that guarantees something has changed inside the engine, and points straight to an out-of-phase cam.
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i have not done that one just yet , but i just now i , i just did the other test you described .

Turn the crank until the points are open. Near ground your coil-wire, .25inch should be good.
Find a small screwdriver with a small shank on it. remove the rotor. Turn the key to run.
Now short the backside of the point arm to the base plate, with a plunge and recoil action. That is to say, your screwdriver will be acting like the points. You should see a tiny spark on the screwdriver tip during the action, and a simultaneous spark at the near-grounded coilwire.

it DID get tiny sparks at the small screwdriver and tiny sparks at the near grounded .25inch coil wire . does that mean the five things that could be wrong if there was no tiny sparks you mentioned are all not wrong ?
 
Ballast Resistors are one of the first things that fail with the points ignitions.
Carry a spare in your glove box.
 
further update . today i tested the coil disconnected from everything , out of the car . both primary "sides" ( post to post ) they read 4.3 ohms in the 200 position of the multimeter . the secondary ( post to center tower ) read 8.25 with the multimeter in the 20k position . since a manual and someone on here said it should be between 1.34 and 1.79 primary and 8 - 12000 secondary . i decided to test a spare coli i have . it tested 1.8 ( 200 position ) primarys and 9.09 ( 20k position ) secondary . so i put that spare coil in the car . again no start , but this time i could not get the coil to spark at all hooked up normally ( i think it did previously with old coil ) but it did spark with the coil hotwired and attached to the spark tester ( set at 3/8 inch or more like 1/4th inch ) looked pretty good , but too bright outside to see it too great . then i did the same with the number 1 spark plug wire and did not notice any spark . but maybe did not wait long enough . after this i disconnected the wires ( firewall and radio static canister thing ) from the coil negative and hotwired the coil again and this time got spark from both the coil ( again looked pretty good , but again too bright outside to see it great , but had thin long sparks that would occasionally go orange ) AND a tiny blue spark at the spark plug wire . tester set to .25 inch . but would only be once per few cranks , which i guess is because the rotor has to spin around again to that tower . still would not start though .

the battery showed 12.75 connected normally as it sits , dropped to about 10.50 ish when cranking . this battery is 3 years old , but have been cranking and cranking etc. for a week now . i was going to charge it tomorrow . not sure how that is affecting things .

i am starting to suspect the wire that comes off the firewall going to coil negative , might be another part of the issue . it looks a little corroded where the wires are exposed . can that wire be tested with a multimeter ? or powered test light ? ballast connected or not ? key on or off ? cranking etc. ?

i cannot yet check the timing chain because i don't have the right sized socket , or breaker bar , yet to rotate the crankshaft . so , unless theres another way , it will be some time before i can try the test AJ/FormS suggested . i did try the other no spark test he suggested when the old coil was hooked up , but did get tiny sparks from the plunging screwdriver to the points arm and plate and the near grounded wire . what does that mean ? does that rule out anything ?

as some have suggested , i was going to try a different cap , rotor , condenser etc . as i have extras around here , some unused , some were working when removed , but did not want to get too far ahead without some input from everyone , especially about that wire from the firewall , and what the coil is or is not doing . thank you all for your time and patience . i am unfamiliar with alot of this electrical stuff .
 
moparjon said:
i am starting to suspect the wire that comes off the firewall going to coil negative , might be another part of the issue . it looks a little corroded where the wires are exposed . can that wire be tested with a multimeter ? or powered test light ? ballast connected or not ? key on or off ? cranking etc. ?
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The BLUE wire from the firewall goes to the coil Positive.
The coil Negative, goes to the points.
The coil is just a transformer, that multiplies the battery voltage high enough to spark the plugs which is about 16000 volts or more. If you run the coil in reverse polarity, I have no idea how that will affect things; I've never tried it.lol.

To test for power at the coil +, the points have to be separated; otherwise the power runs straight thru the coil to ground, and the voltmeter reading will be wrong.. At key-on, with a cold ballast, you should have near battery voltage there. If you don't, your condenser may be bad; so the next test is to take it out of the circuit.
With the points open and the condenser out of circuit, both sides of the coil should have nearly the same voltage.
The ballast is a choke. When cold it lets most of the battery voltage thru. As it heats up, it chokes the incoming voltage down to in the range of 7 to maybe as much a 9v, while the regulator is pouring the coals to the battery.

You can test the timing chain slack using the fan to rotate the engine. You only need to rotate the crank a few degrees in either direction until you feel resistance, and then go the other way until you again get resistance. Watch the rotor; if it moves, you rocked it too far. Start over. If the belt slips, make it stop, lol.
With a new chain, and ideally, this should be ZERO degrees on the balancer. I have taken apart engines that had 10* rock on the balancer and still ran. 4 to 6 on a hi-miler is more common

Btw.
I have a 318 here with a jumped chain. The pistons came around and bent the valves; now it has no compression.
 
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If you a wire coming off the fire wall going to the - negative side of the coil probably an old tachometer wire. And yes the can short out too. You should disconnect that wire.
 
This really is just dumbfounding, this should be a 10 minute diagnostic job with a hot wire from the battery. We even have a video posted on how to do it.

We knew how to do all of this points stuff when we were 16 years old, 50 years ago. Motorcycles, cars, trucks, tractors, lawn mowers you name it.

Keep digging into it, that is how you learn. If you don't know, you don't know.
 
whoops , yes i meant firewall wire to positive post on coil . been a long day . mine looks brown , what does that do ? is it related to the ballast ?


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I would simplify all this down to bare bones. I would de-wire EVERYTHING and "re" wire it "hot wire" to get the minimum so to run it

List of possibilities "so far as I can remember" and in NO order
1...Wiring problem. Either not enough power, something causing a break in power, or IS IT THE TACH WIRE to the coil NEG? might be shorted

2....Dist. primary wire--the one that goes to the coil NEG. Could be broken inside, or shorted such as through entry into distributor body. Remove it, examine it, test it

3...Bad points. As much trouble as you've, might be time to just replace them if you have not

4....Bad condenser....See 3 above

5....Bad coil. since you have a second coil, you can sub back and forth. Hooke things up with alligator clips the coil does NOT need to be grounded

6....Double check coil wire, you may have done this.

WHEN TESTING "hot wired" do NOT connect power any longer than necessary, as you may burn points or damage coil.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

At this point you might want to consider yanking the distributor out of the engine. In either case, use ohmeter on the advance plate (the plate where the points mount) and to the engine block to make absolutely sure the advance plate is seeing a ground.

So to test "bare bones" you want the points adjusted, condenser points and dist assembled in engine, and distributor wire to coil NEG. NOTHING else connected to coil.

Open points by bumping engine. With your meter on the coil NEG, hook "alligator clip" power to coil + You should see "same as battery" on meter from coil NEG to ground

Close points by bumping engine. With your meter on coil NEG, and power to coil+ you should now see very little voltage, perhaps 1/2--2V the less the better. This shows the points are closing and CONDUCTING.

If you get this far, I would "again" rig a spark test gap from coil tower to ground. Use a solid core wire even if you have to use a chunk of low voltage wire, "dangling" in air away from metal. Again with power to coil+ crank engine. You should see hot blue spark perhaps 1/2" long. If not, I would gamble on either a new condenser or new coil. Obviously a condenser is cheaper.

Again to sum this up for this "bare bones" test, you have power from batttery direct to coil POS-----coil NEG ONLY run to distributor wire----and your test gap set up on coil tower.

Alternative---do you have a distributor out of ANYTHING else, ANY engine with points? You can use it to check the coil, "rig it" and if it works maybe "rob" that condenser. Does not matter what this is out of any 4, 6, or V8 engine with points.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Alternative coil testing. You can also "rig" a coil to test it. You should have a condenser.


1..Connect condenser shell to battery NEG.
2.. Connect condenser wire to coil NEG
3..Rig your test gap from tower to battery NEG
4..Connect coil + to battery POS

Now connect a alligator clip wire to coil NEG and "tap" it on battery NEG. You should get a snappy spark at the test gap each time.

"Rig" the coil + to a 12V battery.
 
I have not seen where you have VERIFIED that the engine is still in time and the timing chain has not jumped. Remove #1 plug. Remove the coil wire. Have someone bump the engine over with your finger covering #1 plug hole until you just feel compression trying to blow it out. Now, look down at the timing tab on the timing cover and find the mark on the balancer. You will need to turn the engine "on around" a little more and line the mark on the balancer up with the zero on the timing tab. Then take the cap off the distributor. If the rotor is not point to #1 plug wire, the timing has jumped.
 
points checked ( post #55 ) and are fine . engine still in time and not jumped , as below

with good coil hotwired , and swapped out condenser with and old one still did not start . dwell then checked and reset to its happy place at 34 . no start . rechecked spark with tester . sparking good from coil , kinda weak at spark plug wire . then i pulled out of the trunk an old , kinda funky rotor with bent up tab and all . however , i noticed it looked slightly bigger than the 3 months old one that was in the car . i mocked up with an old cap that came off the car from the last tune up and the new rotor could barely reach the contacts ( not exact science here , just holding it in the cap loose ) but then checked the old rotor and it was way close up to the contacts . anyway , put old funky rotor in and it started right up with the number 1 spark wire still attached to the spark tester ( I.E. ran on 7 cylinders ) . i shut it down then . connected the coil positive wires , the number one spark plug wire , and the air cleaner etc . started up great and ran for a half a minute , before i cut it off because i heard what i think is a valve tap . i guess its possible the rotor i recently got was wrong and was just long enough to last a few months , or it failed or something made it fail .

my question now is the valve tap , now i know its been sitting for a week being cranked , so i get there might not be much oil in there up top . plus its really cold out . was only running one minute . the points adjustment should now have changed the timing a little . timing showed just a hair or two after 0 . cold engine at idle ( not fast idle ) . i think i usually have it at 2.5 ( with engine hot ) , but cannot remember if that was before or after 0 . i wrote it down somewhere , but finding that will take another week . the plan now is to get a new rotor ( or two ) , and while at it a condenser , another coil , cap wires points , just to have extras . then with a new rotor etc . warm it up and set the timing . that might take care of the valve tap , but how concerned should i be running it like that for timing it etc ? its not a horrible tap , but i know its not good to hear it at all . i think its just one cylinder , but will check all by the hose/ear method if it doesn't go away quickly after warmup/timing . any suggestions before or after setting the timing ? thanks again everyone . i appreciate everything .
 
0, 2.5 is no place to run the timing, just sayin. Bump it up to at least 5BTC. But that should not keep it from firing. Very tough to diagnose "by remote control." LOL
 
i kinda still don't believe this , but the "new" 3 to 4 months old rotor on the right , the blue one . pictured here with the centers of both measured and lined up side by side with the old white one ( from some years ago ) , the white one's tip is a at least full 1/16th longer . i hope they just gave me the wrong part or the wrong part was in the box . i hope this is not what they are going to be selling now . oddly this short blue one worked just fine for about three or four months . then from what i can tell , it was not making enough contact to start or stay running . put the old bent up white one in , it starts right up and runs good . of course , i looked around a found a new old stock blue streak rotor from the collection of parts , and put that one in . looks exactly like white white one , and has the same dimensions , etc. fired right up too .


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