Points and condenser to CDI (1973.5)

[GJVGC]

Looks like that is also at the right location.
Going to check for continuity from the tach end to distributor end.

[E Sully]

Here is a diagram of the pin out of the electrical console. You should get continuity from the Blk/Prpl wire at the distributor to the back of the tachometer.



Also, here is a wiring diagram showing 73.5 additional wiring, the T CIS differs from the early T, E, and S in 1973. You only need one black relay installed in the console, to control the WUR ( Control Pressure Regulator). The Aux Start relay is not used. The only fuse needed in the rear panel is the defrost relay.

[GJVGC]

Thank you Ed!
Will save that in my archives.
I just tested my tachometer on a local 73 911 and it worked perfectly.
I will check for continuity through the black/purple wire.

[GJVGC]

Another update.

After verifying that the tach is working perfectly on another car and also checking and confirming continuity at the black/purple from the distributor to the tach it is still not working. At all.
I verified the red/black wire at the tach and it is getting 12v. Cleaned the ground wire.
The black/purple wire is getting 5.7v when the car is running.

What else should I be checking?

[timmy2]

I’m betting a high resistance in the black/purple wire somewhere.
Measure resistance(ohms) from points to tach overall. Should be almost zero ohms.

If more than 1 ohm:
1. Unplug both of the 2 14 pin connectors.
2. Check the black/purple wire resistance from the points to the 1st 14 pin connector female pin 9.
3. Check the male pin 9 on back of panel to male pin 8 at second 14 pin connector.
4. And finally female pin 8 of the through body harness to tach.
Report back....

[GJVGC]

Thanks Dennis!

Checked all points for good measure and all measured 0 ohms!

[timmy2]

Check for a good 0 ohm ground at the tach is all I can think of.

[GJVGC]

Dennis,

I got 0hms at the ground as well.
Looking through other threads, could it be the points not sending a strong enough signal?

[timmy2]

What is the voltage at the gauge on the red/black power supply terminal?

[GJVGC]

12.8 v at the red/black wire at the gauge

[timmy2]

Only an on/off pulse signal from points to tach. Are the points good and clean?
Same year car when you tested the tach? Some years have pulse signal conditioners.

[GJVGC]

Yes, the tach was tested on a 1973 car with the same CDI system.
I will check out the points next do you think I should change them out?

[timmy2]

Not sure what you need.
If CDI is working properly measuring the signal and firing correctly, then I don’t know why the tachometer doesn’t like it.
Try swapping CDI units?

[GJVGC]

Update and Fix!

Using the diagram and help on the thread I was able to successfully install the cdi system on the car and fix the non working tach issue.

Checked the gap on the points. Was at .012”!
I cleaned the points and gapped them to .016” and the damn tach started working.
I’m assuming it could not read the signal with the points so close together.
The tach was still a bit bouncy at idle so I ordered new points. Hopefully that will completely take care
Of the issue. Also looking at what to use to replace the points all together.





Thank you all that took time to help.

[HarryD]

Originally Posted by GJVGC

Update and Fix!

Using the diagram and help on the thread I was able to successfully install the cdi system on the car and fix the non working tach issue.

Checked the gap on the points. Was at .012”!
I cleaned the points and gapped them to .016” and the damn tach started working.
I’m assuming it could not read the signal with the points so close together.
The tach was still a bit bouncy at idle so I ordered new points. Hopefully that will completely take care
Of the issue. Also looking at what to use to replace the points all together.





Thank you all that took time to help.

When my top end was done, my mechanic installed a Pertronix Unit. No more gapping points!

[GJVGC]

Im definitely thinking of going to pertronix on this car soon.

I am keeping the points for now to see if new ones completely fix my tach issue.


Is this correct on the places to oil and lube on the distributor?

[Trackrash]

Originally Posted by GJVGC

Im definitely thinking of going to pertronix on this car soon.

I am keeping the points for now to see if new ones completely fix my tach issue.


Is this correct on the places to oil and lube on the distributor?

Yes. A very thin application of grease on the cam.

Also a drop of oil to the pivot on the points.

Make sure there is no play in the distributor's shaft and the advance works freely.

I would recommend using an old fashion dwell meter to check your points and distributor. Rev the motor with the meter installed and confirm the dwell is stable. Now would also be a good time to run it with a timing light just to confirm the correct ignition advance.

[GJVGC]

Thanks Gordon,

Is this where you mention the drop of oil?


I have been lookin for one of those dwell meters and it seems eBay is the place to get one of those. Looks like nobody around sells them new. Old technology I guess.

Thanks!

[HarryD]

Originally Posted by GJVGC

Thanks Gordon,

Is this where you mention the drop of oil?


I have been lookin for one of those dwell meters and it seems eBay is the place to get one of those. Looks like nobody around sells them new. Old technology I guess.

Thanks!

I have never lubricated the pivot on the points in any of my cars. Drop of oil in the center to dizzy shaft (remove plug be fore adding oil) and a thin smear of dizzy grease on the cam.

[Trackrash]

The pivot point is lubed on new points. Looking at the old manuals it does mention to lube the pivot point during a tune up. Probably not a big concern, but worth mentioning.

A better strategy would just be replace with new points and make sure the distributor itself is up to snuff.

If you plan on continuing with the points, and there is no reason, IMO, not to. A dwell meter should be in your tool box.

Once upon a time I let the points rubbing block dry out. Eventually the points gap got smaller. This caused uneven running and it caused my ignition timing to be off. So since then every oil change, or before every track event, I would hook up my dwell meter and timing light to verify everything was up to snuff.

My 911 ran on points with no issues up to last year when I replaced the motor. My '67 Beetle's 09 distributor is still trouble free as well. It's old tech but it still can work.