Marelli distributors... maintenance?

[911T70]

After reading some threads about distributor maintenance and the nasty surprises some find when they inspect theirs, I decided to have a look at mine for the first time. 1970 911Ts are equipped with Marelli S112BX distributors and their design is very different from the Bosch distributors the threads I referred to discuss. I was pleasantly surprised to find that it’s in excellent condition and that there is no evident sign of wear. I am, however, puzzled by how the shaft gets lubrification. I expected to find a felt pad like the Bosch unit has but initially didn’t see one. While cleaning it, I noticed that there is one under a thin metal disk, visible through a semi-circular opening (as can be seen in the attached photo - opening at the 11 o’clock position on the disc).

I did a lot of searching on this forum and elsewhere on the web for information on how to maintain these distributors but haven’t found anything, which really surprises me. Is it because these are maintenance-free? If so, how do they stay lubricated? The felt pad access hole is not easily accessible when installed in the car so adding oil to it as routine maintenance is probably not intended.

Any information about this would be very appreciated!

[AutoXer23]

Subscribing. Currently trying to figure this out myself today.

[911T70]

Originally Posted by AutoXer23

Subscribing. Currently trying to figure this out myself today.

I'm surprised nobody's responded. Marelli distributors were only used for a couple of years so I guess there aren't a lot of them out there on 911s.

[bobb169]

I have Marelli on my 1970. Only thing I noticed was on the plate where the pin for the weights runs on, the plate gets worn.... and the AX works fine on the 1970

[Alfasrule]

I'm an ALFA guy but have 2 cars with this system and many more in the past. Just clean her as you did and check the oil seal below where it says S122BX. Motor oil lubricates the distributor. In ALFA's it connects to the oil pump. Apparently you must have a CDI Bosch box to power the coil. No condenser. I also use a fine soft nail file to sand the contacts of the points just to get the oxidation off, no need to change them if you have a CDI of whatever make. I have placed CDI Boxes in my ALFA's cause of their benefits. I always gap the points on the bench. Finger grease the lob upper left of S122BX, just a layer. Slap her back together and drive. I've had both kinds single and dual points, very reliable distributor. Surprised to see that Porsche used an Italian distributor to power a German car?

[911T70]

Originally Posted by bobb169

I have Marelli on my 1970. Only thing I noticed was on the plate where the pin for the weights runs on, the plate gets worn.... and the AX works fine on the 1970

Do you lubricate the advance mechanism? I've read on other forums that the plate does wear so some sort of lube would prevent that... but the weights also need to move freely, so the type of lube matters, I'm assuming.

[911T70]

Originally Posted by Alfasrule

I'm an ALFA guy but have 2 cars with this system and many more in the past. Just clean her as you did and check the oil seal below where it says S122BX. Motor oil lubricates the distributor. In ALFA's it connects to the oil pump. Apparently you must have a CDI Bosch box to power the coil. No condenser. I also use a fine soft nail file to sand the contacts of the points just to get the oxidation off, no need to change them if you have a CDI of whatever make. I have placed CDI Boxes in my ALFA's cause of their benefits. I always gap the points on the bench. Finger grease the lob upper left of S122BX, just a layer. Slap her back together and drive. I've had both kinds single and dual points, very reliable distributor. Surprised to see that Porsche used an Italian distributor to power a German car?

After a lot of Googling, I did find some posts about Marelli distributors on Ferrari and Alfa forums and saw how some models have a little spout on the side for oiling. Ours have a felt pad that I assume needs to be oiled periodically? The access hole is just not easy to reach when it's installed in the car. I can see how the bottom bushing gets oiled from the oil in the crankcase but how does the top one get oil, other than from the felt pad?

911s also used CDIs in 1970 so the points only switch 12 V to trigger the CDI into discharging. They should last a very long time - mine still look new after a few years.

And yes, I was surprised that an Italian distributor was used by the factory in these cars. I've since read lots of positive things about them and like how simple their design is.

[911T70]

Here's an update to this thread with the answers to all my questions. Not initially getting replies on this forum, I thought of reaching out to Kurt Donohoe, with whom I had a very pleasant and productive interaction when I updated my CDI a couple of years ago. Sarah, Kurt's wife, promptly answered my email with some very useful information and photos. Sarah and Kurt now operate Klassik Automotive Training School, a website and YouTube channel dedicated to air-cooled Porsche maintenance and repair. She informed me that they were preparing a Marelli video and article that would soon be posted. I couldn't believe my good luck with timing! They have just been posted and are definitely worth watching. Make sure to check out their website and YouTube channel - a real ressource for air-cooled DIYers!

https://www.klassikats.com/index.php/2021/03/18/show-some-love-to-your-marelli-ignition-distributor/

[HaroldMHedge]

Great videos and information. I've been following their engine rebuild.

[Hawkeye's-911T]

Hi Michel

I don't know how I missed your thread on Marelli maintenance. The link was a confirmation of my disassembly
procedure & served to eliminate my apprehensions when it came to "popping" the cover plate to access &
're-charge' the lube felt ring in your 2nd photo. Thanks for the info - much appreciated.

Cheers
JB

[911T70]

Yes, this is very useful information for those of us with Marelli distributors - I'm very grateful to Kurt and Sarah. In the past, I was led to believe that these were inferior to the Bosch distributor but my internet search has thought me that they are very good and reliable. Same thing with Zenith carbs vs Webers - I love my Zeniths!

Originally Posted by Hawkeye's-911T

Hi Michel

I don't know how I missed your thread on Marelli maintenance. The link was a confirmation of my disassembly
procedure & served to eliminate my apprehensions when it came to "popping" the cover plate to access &
're-charge' the lube felt ring in your 2nd photo. Thanks for the info - much appreciated.

Cheers
JB