What am I missing?

[John2189 445]

1967 mustang 289 Was running very rough. I replaced points, cond, rotor, and cap. Started it up, ran a bit better. Was warming it up to adjust carb, after 10-15 minutes, it just stopped running. Would not start again, fired some,but then it stopped that. I checked spark, very weak at coil wire. Ran battery down, so put on charger next day I used sandpaper on points and cleaned with paper. Better spark but no spark at spark plug wire. Put old cap and rotor, still no spark. Tried a different coil, no luck. 

What am I missing? I’ve worked on engines for ever. 
John

[squonk 41,038]

Is there a ballast resistor anywhere? 

 

I had a Dodge 318 that drove me nuts with a spark issue. Turned into a worn out /  jumped timing chain. Sounds nutty but that was the issue.

[stevasaurus 22,711]

Dodges always had timing chain issues...especially the slant 6.     Sure sounds like a coil issue, could be a bad condenser.  Maybe bad coil wire.  Are you sure the gap is correct??    0.017

[John2189 445]

20 minutes ago, squonk said:

Is there a ballast resistor anywhere? 

 

I had a Dodge 318 that drove me nuts with a spark issue. Turned into a worn out /  jumped timing chain. Sounds nutty but that was the issue.

No resistor

[John2189 445]

3 minutes ago, stevasaurus said:

Dodges always had timing chain issues...especially the slant 6.     Sure sounds like a coil issue, could be a bad condenser.  Maybe bad coil wire.  Are you sure the gap is correct??    0.017

Yes .017.   It had a carbon coil wire, I put a wire one on. Was thinking about putting the old condenser on. Will try that tomorrow. Tried a different coil no change. 

[stevasaurus 22,711]

The guys keep talking about buying new parts that are bad.  I would try the old points & condenser (but one at a time).  Obviously grounds are important, but so are wire leads that may be corroded under the insulation.  Or high resistance opens (broken wire in the insulation).  Don't suppose you have a picture of that Bad Boy??  

[squonk 41,038]

Any play in the distributor shaft. Too much side to side play could cause erratic points gap with the points cam wobbling all over. 

[John2189 445]

22 minutes ago, squonk said:

Any play in the distributor shaft. Too much side to side play could cause erratic points gap with the points cam wobbling all over. 

Dist shaft is good 

[John2189 445]

51 minutes ago, stevasaurus said:

The guys keep talking about buying new parts that are bad.  I would try the old points & condenser (but one at a time).  Obviously grounds are important, but so are wire leads that may be corroded under the insulation.  Or high resistance opens (broken wire in the insulation).  Don't suppose you have a picture of that Bad Boy??  

Yes I’m going to try the old condenser tomorrow.
 It my neighbors, it was her dads. It is green convertible. It was a 4 speed, but she had it changed to automatic. I told her to be sure to get all the parts back. So the matching numbers would stay with it. 

[ranger 1,746]

Can you disconnect the “live”connection to the coil and connect a temporary “jump” wire to battery positive, assuming negative ground. Then see if spark improves?  this should indicate whether ignition feed circuits are suspect, or ok. Although it does seem to be a condenser issue. Having said this, does this car have a ballast resisted ignition system, and the new coil is 12v. One car I had (Ford) had a ballast system, P.O. had fitted a new starter which didn’t have the extra connection to supply 12v to coil whilst starter is operating! The engine would start first time when cold, but would not even fire when hot, until it had cooled down for a while, then it was ok, when running it was fine.

[squonk 41,038]

67 Mustang is supposed to have a wire resistor style in the harness. No firewall resistor. That resistor wire could be bad dropping primary voltage to the coil.

[ranger 1,746]

1 minute ago, squonk said:

67 Mustang is supposed to have a wire resistor style in the harness. No firewall resistor. That resistor wire could be bad dropping primary voltage to the coil.

Thats what I’m thinking. Having worked as an ‘R.A.C. ( Royal Automobile Club), mobile patrolman in the late 1970s, I have lost count of the number of condensers I have changed at the side of the road on vehicles showing these symptoms. Also it seems, the quality of some replacement points and condensers nowadays can equal that of Chinese drill bits!

Doug

[ranger 1,746]

2 hours ago, John2189 said:

Yes I’m going to try the old condenser tomorrow.
 It my neighbors, it was her dads. It is green convertible. It was a 4 speed, but she had it changed to automatic. I told her to be sure to get all the parts back. So the matching numbers would stay with it. 

I can see what the problem is now, the car is 🍀GREEN!!! It should be 🌺RED!!! 

[The Tuul Crib 7,336]

Sounds like a timing issue. Those had a 

plastic timing gear mounted to the camshaft. Simple fix

[gt14rider 749]

Check and clean all grounding points, I had a problem with my 79 Ford bronco, had a bad eng ground and some other wires were rotted to dust in the middle, but plastic casings looked ok.

Has the car been sitting or driver?

[John2189 445]

4 hours ago, gt14rider said:

Check and clean all grounding points, I had a problem with my 79 Ford bronco, had a bad eng ground and some other wires were rotted to dust in the middle, but plastic casings looked ok.

Has the car been sitting or driver?

It’s been running 

[John2189 445]

Ok put the old condenser in, it started right up. 

[John2189 445]

Back to the mustang.  It has two cylinders not fireing. # 1  and 6. New wires didn’t help. I put a known good plug in no different. Compression was 90#.  
 

what next? Remove valve covers to make sure valves are working? 

[squonk 41,038]

5 hours ago, John2189 said:

Back to the mustang.  It has two cylinders not fireing. # 1  and 6. New wires didn’t help. I put a known good plug in no different. Compression was 90#.  
 

what next? Remove valve covers to make sure valves are working? 

Look for a vacuum leak at those cylinders. Check where the intake manifold deals on the heads and check any vacuum hoses and devices that may be plugged into the intake runner for those cylinders. No.1 is on the pass side and No. 6 is the 2nd back on the drivers side. So they are near each other on the intake.I have had countless cars in the shop with a lean cylinder miss. If ok pull the covers. Could be a worn cam lobe on the intake valve.

Edited April 23, 2021 by squonk