Ignition breakdown

[Frankr]

Get good electronic system and store that old shit in a box. No worries for next 20 years. https://electromotive.com/our-products/xdi-ignition/

[edmayo]

How long has it been doing this? Was any work performed just prior to this occurrence? When was the last time the point gap was checked? Unlikely it is rotor, when cut-out occurs it is rapid 'missing' effect. Disconnect tach from distributor to ensure it is not tach problem. Did this 'suddenly ' appear , or has it been a gradual symptom? Do you have the original Bosch black coil and Bosch C.D. box? Does this occur right away, or does it have to be driven for a while?

[classic]

How long has it been doing this? Was any work performed just prior to this occurrence? When was the last time the point gap was checked? Unlikely it is rotor, when cut-out occurs it is rapid 'missing' effect. Disconnect tach from distributor to ensure it is not tach problem. Did this 'suddenly ' appear , or has it been a gradual symptom? Do you have the original Bosch black coil and Bosch C.D. box? Does this occur right away, or does it have to be driven for a while?

Ed,

First occurred a few days ago, and no, no work done on the car as such.....going to go right over the Dizzy today and check everything, I’ve got a new rotor, cap and point set ready. Everything except a spare CDS, but don’t want to just throw parts at it, as then I won’t know what was causing the fault, going through one at a time. The original coil NOS 006 Ohmed out all good, but I swapped it out with my spare......same problem, so have put the original back in place.

When it occurs it’s rapid, under load passing through 3500rpm it drops back to about 1500rpm and starts stumbling with lack of power, if I keep it under 3500rpm you wouldn’t know there’s a problem......limped home after a test drive yesterday.

I haven’t tried disconnecting the tach, I’ll try that today......would the Tach send a signal back when it’s red lining?

My car is a late 69T running points and a CDS.....I put a new loom into the CDS when I restored it about 6 years ago, as the original was a bit brittle. Running a rebuilt Marelli with a relatively new cap and rotor from PartsKlassik for the last few years without a problem.

It suddenly appeared, and yes Bosch CDS and black coil, and the intermediate unit, for the tachometer......it appears right away, I thought about heat and the CDS, but tried it yesterday cold, and got it to repeat the fault less then 100m down the road.

CDS whistles away, and no breakdown in ignition until 3500rpm......I can’t get it to fault in the garage, only under load.

[classic]

Points checked .4mm or .016 in. Marelli

Dwell checked 39°

Timing looks good, waiting for it to warm up a little before taking it to 6000 RPM. Tweeted a bit, but all looked good.

Pulled the plugs, slight electrode erosion, but gaps look ok.... I’ve got a new set here, so might just swap them out.

It’s too late here for a test run, will get that done tomorrow

[edmayo]

If I were working on it in my shop I would be trying a known good C.D. box. I know,,,it's easy to say that when I have known good one to try, but I really think that would be a good first step. If that option doesn't exist and no other faults are found I'd send the box to 'Ashlock Tech' he can test and/or rebuild as necessary.

[classic]

Ed,

Thanks for the response. It is looking like it’s the CDS.......about to take her for a run and see if anything I did yesterday has improved the situation.

[classic]

To close off the thread. It would appear that my work yesterday was a success, only problem is I don’t know what I did to fix it.......just a good tuneup I guess....

[edmayo]

If I had to guess it was the points,,,,but glad you got it.

[classic]

Thanks for your assistance........I hate it when you don’t know exactly what it was.....

Anyway happy motoring.

[Ratech]

Have you verified the points are properly adjusted. Often they get neglected and the rubbing block wears so much that they barely open.