Marelli Centrfifugal Advance

[Hawkeye]

This is my Marelli S112BX in a 2.2L 1970 911T. I will be removing the whole unit in a few days time
& hopefully will be using an aftermarket rebuild package to upgrade.

If possible, how does one remove the advance cam “C” to facilitate a fill or repair to the wear
notches/grooves “A” & “B” with a suitable weld material? The subsequent material build-up would
then be filed to match the proper contour of the cam.

It is my understanding this advance distributor cam repair procedure has been successfully used
in the past. I am however, somewhat mystified as to the proper method to separate the cam
portion without incurring damage to any of the component parts of the cam & its driver.
The weights themselves appear to be in good condition.

I would like to be sure & know my options before I proceed on this project so any thoughts
& suggestions at this time will be & are most appreciated.

Thanks & Cheers
JB

[Jerry L]

I think the unit C now basically part of the shaft, it does not come off, I have I think the same unit out of my 71, 2.2 and I pulled it due to wear in the advance weights and put in the Bosch unit. I would have yo look at mine again to see if the part C was actually also part of the problem.
to weld and reshape C you will have to completely disassemble the unit, remove the drive gear (press out pin) and pull out the shaft assy. Then it becomes while you are in there replace / assure bushings in the housing have proper fit to the shaft. properly reshaping C looks to be a big issue to get it correct.
Drop me a note if you want pics of the one I have.

Good luck

[Hawkeye]

Hi Jerry

Belated Happy New Year to you & yours.

As you pointed out, things are & as expected. The complete tear-down of the
distributor will be necessary to facilitate any possibility of any sort of remedial
work to the worn portion of the 'C' cam piece. At first glance, it does look as
though the cam & its driver are a 'one piece' unit & was not designed to be separated
into its constituent component parts.

The intention of my post was to elicit thoughts & advice before I start the process
of removing the distributor & the eventual installation of the aftermarket upgrade kit.

Your response & input is appreciated - many Thanks

Cheers
JB

[Jerry L]

Pulled mine off the shelf, same issues a wear groove on C right at your leader lines for A & B, when I first pulled it to examine it you can feel a solid notch / kink when advancing the top plate, also on mine I have two different springs as it appears you do as well on wire diameter. But on mine in the one pic showing both springs the one on the left is not only a much larger wire dia but the "hooks / loops" are more of a U vs a loop and the spring does not engage until some point fairly well into the advance / RPM (I don't have a sun machine) if you look at the other pic you can see a definite notch BUT to me it does not look like a normal wear radius I would expect to see. so with the weird feel CLICK as it falls over the step and the Odd to me spring. I bought the Bosch E & S (006, 007? from memry) over a couple months (this was about 10 years ago :-) and the Merelli has been in a box till tonight.
My 71 2.2 T had had some nice modifications done to it before bought it, I tried both Bosch distributors and settled on the S curve.
I am not sure what parts are in the Merelli upgrade or who has them, either way You need someone with a sun machine to help Sort it out.

Let me know if I can help, I do have a friend in TX with a sun machine and may be interested in playing with it.

Best Regards