Early 1969 911 help needed (distributor related)

[Vintage Racer]

I can't seem to get the stock distributor working well. The timing light wanders around at different Rpm levels.

I can't find the fault except that the original distributor has too much play in it? The plugs seem good as well as the plug wires.

I have no ability on rebuilding it.

[Jerry L]

Is your idle / running conditions changing as well? Also I see the vacuum advance, it should be disconnected and the vacuum line plugged going back to the manifold (golf T works well, may have to shave the diameter if too big) this should assure it is hooked up right and it is not the the timing light bouncing.
If engine running speed is bouncing as well and Vacuum advance is disconnected, pull the cap, look at the points rub block and the cam lobes to be clean and in good condition. next would be play radial (as twisting it) and also vertical (up & down as pulling pushing) I don't have numbers for the play, traveling and no manual.
How long has it been going on? I would eliminate all other items before assuming the shaft play. Have you replaced points? If all else looks good, distributor is easy enough to pull out, just rotate the motor to TDC on #1 for reference before you do.
Lots of competent people out there to do a rebuild "IF" needed. and if you do, maybe have the vacuum advance removed,

Regards

[Vintage Racer]

Thanks,
I printed your post and will check it again. I did forget to disconnect/plug the vacuum. I'll go back and re-do everything.

The points, cap, and inside parts are new and/or clean. I do remember how to get to TDC before removing it.

[Frank Beck]

MSD by any chance?

[daniel911T]

I have a late '69 911T and have had lots of distributor problems through the years. I have exactly the problem you're talking about right now at 6KRPM the timing mark dances around quite a bit. In my case, I'm pretty sure I've isolated it to my Pertronix unit, which I plan on removing in the near future. I also think my distributor is suffering from mechanical wear - it has moving parts, it won't last forever.

I've taken apart a 914/6 distributor that had a rev limiting rotor that had disintegrated while running. The owner had removed the big stuff, but some of the smaller bits had worked their way down into the advance mechanism deeper inside. A thorough disassembly, cleaning, and lubrication took care of that issue completely. A car that was missing under load and hard to start became instantly well behaved.

As for my car, I'm installing one of these when I get home: https://123ignitionusa.com/porsche-9...pin-yrs-65-71/

I've was first exposed to 123ignition's products when working on a friend's Citroen 2CV. It's a really elegant solution that seems to generate a very accurate timing pulse. Also, with a cost of $500, it's cheaper than a used distributor, or even a rebuild on your existing one. I'll definitely do a full write up on my experience when I install and tune the distributor.

[daniel911T]

Could you please post the part number from the distributor? I am about 99% sure none of the early cars had vacuum mechanisms, which makes me very curious what you have there.

[Jerry L]

I had that thought the other day when writing, I have a 71 that I had bought both a E & S (006 007?) Traveling and don't remember, to get rid of the Merelli that had wear in the V of the advance weights and nothing with Vacuum advance. But thinking 68 on many cars was the start of vacuum advance or rather Vacuum Retard.

Regards

[Vintage Racer]

I have a late '69 911T and have had lots of distributor problems through the years. I have exactly the problem you're talking about right now at 6KRPM the timing mark dances around quite a bit.

My situation is around mid-Rpm's (just about when the advance should kick the timing forward).

When the throttle is floored, the car pulls hard until around ~6500 Rpm when I back off.

[daniel911T]

The stock distributor has a dual advance mechanism - it purposely has a flat spot. The advance has two sets of weights to make the stepped curve.


If you have a stuck weight or broken spring or the shaft is binding, any of those things can cause the symptom you're describing,

Your best bet is to remove the distributor, disassemble, clean, and carefully reassemble. Be sure to get new points, cap, and rotor. Re-install and test.

There are great videos on YouTube of the disassembly process. Check this website for a wealth of early Bosch distributor info:http://www.sparkingplugs.com/9.html

hope it helps!

[NZVW]

Hi Doc,
Hope you get this annoying gremlin resolved.
Some solid advise been given out here and Im sure you will resolve it
All the best.