Magneti Marelli distributor parts breakdown

Hi all, i need a little help in finding Magneti Marelli illustrated parts breakdown, or overhaul manuals, parts cross references and the like. I have Marelli distributors like S85, S129, S125, S129 and even tho i have a good feel for the correct procedures for overhauling these, i would like some period documentation. I cant find any! Any language is fine.
thanks
Craig

Magneti Marelli spinterogeno, contatti, condensatore
PS - can anyone explain the number/letter stamping on a 60's or 70's era distributor? not the S85C, but the 7L or 4M.

 

thanks Kerry, this is a great poster! i am wanting to understand the commonality of Marelli parts, so i think what is needed is a parts breakdown with numbers for all parts. i believe the points, condensor, rotor, cap are all listed at various parts suppliers.....numbers like 71007106 for points, 7038801 for rotor..and so forth
What are the numbers for -
1) rotating shaft/drum
2) flyweight
3) springs
4) cam, bearings, caps, and all
etc

here is a photo of an S85 shaft assembly i am working on and the dimensions i found. How does this compare to someone elses Marelli?
thanks for any help
Craig
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John, i am pretty sure the Nylon or Delrin bushing sets the total centrifugal advance the distributor will provide. Leaving the bushing out might allow way more advance than what is desired. Looks to be easily fabbed, it is a tight but hand removable plastic bushing, color is unimportant.

the upper bearing, looks to me to be, a 608 RS (8x22x7 sealed one side)if an early distributor, or a 628 2RS if later slightly larger.

lower bearing measures at 15x35x14 which could be 62203 2RS, but would rather see someone back that up.
here is a photo of a bushing in a Marelli S85 with 9.5 degrees advance.
Craig
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John, you are correct, the bushing is only setting the start point further out, there by limiting travel. I am only familiar with 1966 thru 1972 applications at this time and these have all used a nylon spacer ring. It is quite possible a 1959 design might not require the spacer ring. I have always thought it provided a cushion when dropping in speed and the weights retract, but i bet this is not required. lack of service and poor lubrication tend to be the big culprits in a Marelli advance unit.

I am amazed at all the threads before on this subject and glad to see them. It would seem that there has been enough work on this subject to have identified the exact spring rates and preloads to make this a simpler task, but it looks like this is a closely guarded secret. Maybe the flyweights are not consistant weights. Or maybe just a lot of inconsistant fits that make it a custom process everytime.

I see lots of Marelli numbers listed at Dennis McCann's site allferrariparts.com........where did these Marelli numbers come from? where the catalog? the IPB?
Craig

 

Hi group, just recieved a set of new Marelli weights from GTCP. I stamped them 1 thru 4 on them so i can keep track. Part number from GTCP is 70382001 which may be the Marelli number, sure seems to be. All the flyweights have a about 58 gram weight. Actually i did a quick check on my old Ohaus 2610 and find 57.4, 58.0, 58.3, and 58.3. The pivot fit (the bore hole in the weight) on my old S85C pins was too tight to put on when i received them. I worried how i would size them with elaborate visions of expandable reamers and small bore hole measuring equipment. I wrapped a couple wraps of 600 grit 3M wetodry around an appropriate wooden dowel stick and within 30 seconds had a, like new, drop-on fit on the old pin. The internal radius of the new flyweight that rides against the black nylon spacer is not quite the same as my old weights, just slightly different, not allowing as much radial swing. It appears the new bronze weight could be sanded at this radius to match the old weights, or the nylon could be reduced in OD.

Has anyone had experience in fitting new weights?
Is there any experience with testing the advance mechanism for advance travel prior to full assembly with springs? Seems logical to fasten a pointer to the cam and a degree wheel to the drum and wig wag for travel limits. Has anyone done this? Seems this should be 9.5 or 10 degrees?
Should i be worried about the dynamic balance specs with the weights? big end/little end? is the radius too small and the weight difference too small to worry with this detail?
thanks for any help
Craig
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Here is what i need to remove from the new weight to match the old. The new weights are 58 gram, the old are 53 gram. The amount of material to be removed would seem to be about 2 grams at most. I am still planning how to test the old weights and establish current available degrees, then test travel with new weights prior to shaping, then shape new weights until correct travel established.

If a new weight is installed on one side and an old weight installed on the other, it becomes pretty obvious that the travel has been reduced by the new weight shape.

For the engineers in the group, Is the relationship between centrifugal force and rotational speed a linear one? so the springs should be a single rate rather than a progressive increasing rate?

i rated my current springs with one being 1.75Kg/mm and the other 1.3Kg/mm. both have a travel capability of 7mm, but only 3-4 is required to satisfy actual flyweight travel.

I am not satisfied with the length of the pins, they seem 3mm short and a cause of failure in this Marelli S85. Anyone have a source or solution for this?
Thanks
Craig
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Hi Marelli tuners, i devised a quick, easy way to determine what advance travel your Marelli will provide once you have disassembled your distributor for repairs and are now fitting new parts. i printed out a 7" paperboard degree wheel off the internet, cut a hole in the center to press fit over the top step on the rotating point cam, set the drumshaft/weights/followers/points cam up in a vertical position. i fixed a steel rule to use as a pointer and actually the paperboard wheel laid on top of the rule for edge support. Sounds a little lo tech, i had planned to use a laser pointer against a white wall, but i got hung up on quickly scaling 0-20degree on a flat surface, how far away, etc.

Anyway, the old weight set wig wagged a 12 degree advance travel.
The new, fresh weight set wig wagged a 8.5 degree advance travel.
Locking the weights in place shows a 0.5 degree wig wag reading for clearances between pins/followers/slots.

in the midst of this i decided to print out a bigger cardboard wheel for a finer check so I a printed a 10" partial and placed it over the 7" ......much better..... i may go bigger as well. 12" or 300mm.
see - http://www.machinerycleanery.com/UniversalTimingDisc.bmp

The test was run without springs, so the clearance or runout must be factored in. Seems the old set will do 11.5 and the new set 8 degrees. I am testing a S85C listed as providing 9.5 degree advance, my measurements show the old set now provides 11.5. what do you think on the new weights - a rat tail file and a vise? or something more sophisticated?

Certainly spinning this finished distributor on a tester will give additional results and data, but it seemed logical that the total travel could be measured prior to full assembly.
i will try and get a photo of this highly professional test setup
i am happy with what i see for outcome on this S85 Marelli, so now i will open up the other Marelli S85 and see what up.
Craig

 

where can i find the Marelli advance curves for a variety of Ferrari using Marelli distributors with either a V12 or V6 configuration? 275, 250, 246, 206? is there any ignition guru reference website that specializes in Marelli work?
thanks for any help
Craig