Some background 1st

I have a 69 455. I had some misfires before so I replaced all ignition stuff:Coil, points, plugs, condeser, wires, etc ec tuned to stock specs..

Checked for continuity, shorts, grounds, etc ete per 69 Olds chassis manual


RAN GREAT!

20mi later, coming home from a car show it started running so rough I had to have a tow.


I checked the points gap, connections, etc. still the same..

Pulled the cap, pulled coil spark wire so I could hold it to see spark, turned ignition on, used a paint stick to open and close points.

added a 12v DC light bulb on coil plus side,

Sparked for a while and seemed OK, bulb always lit.

checked points again, put cap back on, only a few hits, would not start.



OK then removed negative side wire from distributor and added a separate wire, to use as a ground.

With ignition on, I held the coil spark wire 1/4" from ground and grounded out the negative side of coil simulating points opening and closing.

NO spark

is this a good way to test coil? Did I kill it??


not convinced coil was the original problem of it dying, I've done a ton of points cars over the years, always be able to solve issues.. Driving me crazy?

Yeah i read erics post on points troubleshooting

Advice

Update

measured coil + to - terminals got 1.01 Ohms, Measured + to center(spark) terminal measured 10K Ohms

took off stock wires to coil + and - terminals

added a wire to - side and also ran jumper cable from + side to + battery terminal, grounded - side intermittently like points(sparks noticed when grounding) held center spark(2ndary) wire 1/4" near a ground. only very occasional weak spark noticed, even with Ohm measurement is coil shot?????, am I doing test correctly???



Even if the coil passes Ohm test, can it still be bad??? No sparK?

 

Sounds like a bad coil.

They're cheap, if you don't already have a milk crate full of 'em.

You should always carry one as a spare. (Okay, now I've got to go out and see if I've got a spare one in my car...).

- Eric

 

OK replaced the coil, maybe I blew out out old one trying to test it.

Understand i was driving it when it flaked out and starting running real rough.

Again everything new: cap, plugs, points, rotor, condenser, etc etc

took distributor out.


checked ground leads, coil to distributor lead, points, condenser, etc for shorts and continuity, resistance etc

cap fit to distributor

hooked a light bulb to + side of coil, always light while cranking, nice and bright. also on with just ignition on...


all seems good

set the points with distributor out. to spec .016

Put a timing light on #1, had someone crank it. no spark, zip, nada

took off coil spark wire to distributor.

put a spark plug into this wire

had son crank, seems to be sparking but maybe a little weak again NEW COIL

cap shows no traces, or cracks

again new plug wires and everything


put back together, no spark for #1 via timing light WTF

this has me baffled

 

Okay, it's time to read through this thread, and follow the procedure:

https://classicoldsmobile.com/forums...-ignition.html

It's organized and complete, so we won't be feeding you bits and pieces.

- Eric

 

 

Yes I read this and thought I had followed it thoroughly before I started this thread.

OK more testing

I pulled of #1 wire and put a new spark plug into the wire,

had someone crank it.

I do see some firing of it.

Checked TDC against the timing mark on Harmonic balancer, checks out OK.

I then pulled the distributor cap off and got the rotor to line up with #1 wire.

marked cap notch so I know where to line up to distributor notch. locked it down.

put plug wire back on #1

Had someone crank it

had a few hits

moved distributor slightly clockwise and counterclockwise

again a few hits, but still not running. just like it did when this problem first started..

dumped some gas down carb, same..

Yes eric thought I when through everythine, read '69 Olds manual as well

these are some primitive ignition systems it shouldn't be this hard, i've done these quite a bit

at my wits end...

 

Check all grounds?

 

What is your dwell?

 

I did a continuity check from the breaker plate to the body of the distributor, to the engine, to the Neg side of battery

all good

 

In order to get this figured out, you have to isolate each component of the system and check each one systematically.

I would start at one end, whichever you prefer, and confirm each necessary characteristic:

• +12.5-13.5V at coil (+) with points open,
• +9v, more or less, at coil (+) with points closed,
• Less than 1 ohm resistance between points plate and battery (-),
• Move points plate through its arc (suck on and release vacuum advance) and confirm no resistance with meter, then re-confirm no flickering with a test light from +12V to the points plate,
• Zero resistance through points,
• Infinite resistance through condenser,
• Check that coil is well grounded, connect spark plug wire to coil and secure other end about 3/4" from ground, connect jumper from (+) to battery (+) intermittently and look for spark each time you pull (+) wire away from battery.
• Connect coil to car normally, continue previous spark plug wire connection, turn on ignition, open and close points with a screwdriver and look for consistent spark,
• Continue with same arrangement, but now crank engine over and look for consistent spark at end of wire 4 times per revolution,
• At this point, connect dwell meter and confirm 30 degree dwell angle,
• If everything is perfect at this point, try connecting all spark plugs to their wires, placing each one in a visible location in contact with ground, installing distributor cap, and cranking engine to confirm spark at all plugs (this step is massive overkill, and not a great test of your plugs and wires, but it may tell you something if you're desperate).
• As a last chance, if all else fails, find someone with an oscilloscope and see what the waveform says.

If none of that works, replace the condenser.

- Eric

 

 

Eric,

thanks for your ideas. I REALLY appreaciate it

I pulled an Olds HEI distributor/plug wires from a working '79 Olds 350. Ran a positive bat + to Bat side of HEI. Checked TDC, fired right up matter of fact running REALLY good... no heed to curve,e tc et c it just frickin' works at least I can now move it in an out of garage as my real project is rebuilding 79 Cutlass suspension, so I need this side track like a hole in the head.

I had one guy tell me it skipped a tooth.. don't think so.

so the problem is with the old coil type ignition. Will go through your list again you sent.

But now I have a way to at least move it..


never had a points system be so much of a PITA before I've done quite a few in my old fart years....

 

You should be able to do all or most of that testing off of the car - just spin the distributor gear instead of cranking the engine.

- Eric

 

OK think I finally got it one of the welds holding the breaker plate was broken... very illusive would run great for a while.. then not, reset points then OK again for a while.. replaced plate, so far so good. thanks everyones help...

 

If possible, I think many of us would like to see a picture of this, so that we know what to look for should we ever encounter it.

And I, personally, think it's great that you took the time and energy to finally run down this problem once you had the time, and truly figure it out, rather than just saying "Bad distributor," tossing it over your shoulder, and never really knowing what happened/

Thanks for sticking with this, since your troubleshooting information may be helpful to people in the future.

- Eric

 

Great thread and also good info on the actual problem.

 

Some notes:

Be sure you use a ballast resistor, or resistor wire in the vehicle harness, if you're vehicle has one. The idea is: full voltage switched and supplied from the starter solenoid when cranking to start, then ±8v running once engine has started, or ±8v 'key on' voltage measured at coil, so you have actually two wires connected to coil primary connection. If you run un-ballasted supply voltage to coil while running for any length of time, the coil fails in a short time, although I had one last a season finally stranding me at the store on a hot day. The bottom of most quality OEM type coils have a popper like a soup can, and when it is popped out in the center indicating it has been overheated, discard it.

The HEI you installed must have full voltage, meaning no voltage drop when running, although it bears mentioning many end user installed GM HEI systems have been running for decades through a factory resistance wire in older cars.

If you have a liquid filled coil (which you can hear when you shake it), be careful about mounting the coil 'tower up'. The three connections must remain immersed in the oil, or will overheat and cause intermittent hard to trace trouble. Many aftermarket round coils fail installed in factory mounting brackets for this reason.

So many times intermittent trouble is traced to the coil being connected backwards: it should be '+' is where supply voltage is connected, '-' is where distributor wire is connected. Radio noise condensers or 'suppressors' might be connected to either side of the coil depending on what noise situation generally on a AM broadcast receiver is dealt with.

Hold your plug gap to .035 maximum. Wide gaps stress every component in any ignition system, and most of us are not racing, chasing every single last HP.

Inspect the points set after a failure like this, and look for migration of the contact material from one contact to the other, like a pit in one and a identical bump in the other. This can happen pretty quickly if the condenser value in mf is a mile off, or also rarely perhaps some coil problem. In the old days ignition men would check the points and perhaps choose a condenser from a chart of a different value, if the points wear is not even. This is why if your point set wears well it is unwise to change the condenser unless it fails. Keep a spare points set, condenser and screwdriver in the vehicle.

If you know what specs the coil you have should produce, you can use a coil tester, if you can find one. I have a old Herbrand, it has a buzzer inside to act as a points set, and a gap mounted on a wheel which you turn causing the gap to become larger. It should produce a quality spark color up to a certain specified gap. This test can be very hard on a coil especially a older coil which may have some part number cash value, so be careful. Here is a Snap-On:

 

Thanks for that picture, ColdWar.

I have one of those, and have used it, but the printing is mostly worn off, and it's nice to be able to see what it used to say.

- Eric

 

Yw

 

No photo.. I sent the distributor to

http://www.nelsonspecialties.com/


Even so, it took a few times to find the issue..


Had a curve check done and rebuild, got it back. Rechecked point gap. Dwell, etc After a while same issue..

Runs rougher , then rougher, then stop.


One weld broken on the breaker plate underneath. eeeerrrrrrr...!!!


it is a correct number distributor, so I had to make it work.


I've done a zillion points in the day, never seen an issue like this before...