Advance mechanism for Marelli S85C
description
 graphic
20 - snap ring 9.4 ID, 1mm thick

19 - shim washers - 10.15 ID x 14.00 OD x 0.21 thick

18 - triple cam/fork - 10.2 ID x 34.77 tall x 19.23 cam lobe x 8.6 slot x 72.5 grams

17 - bottom washer - 10.12 ID x 14.09 OD x 0.50 thick

16 - slot followers - 7.03 ID x 8.44 across flats x 9.57 small OD x 10.86 large OD x 6.15 total height x 0.86 lip height

15 - pin - steel - 3.58 OD x 6.81 OD head x 22.26 total length x 19.66 shank length

14 - spring cup - steel  - 6.96 ID x 7.98 OD x 9.91 length x 4.30 hole in closed end

13 - spring - steel - 1.10 wire x 6.64 OD x 9 coils x 18.35 length

12 - flyweight - bronze - 11.00 thick,  7.00 pivot hole, 6.95 steel pin dia,
 6.85 steel pin protrude x 54.4 gram weight
7.97 dia bore hole x 14.69 depth, then 3.6 bore thru complete.

shims - variety - steel, brass, copper - 3.60 ID x 6.0 OD x .20, .50, .80 thickness

These are dimensions of used , but servicable pieces.
S85C Marelli #13 flyweight springs - rate tester results -
Spring specs - steel - 1.10 wire x 6.64 OD x 9 coils x 18.35 length
Spring Test Machine - 0.00 -100.00Kg digital spring tester
position
mm
 spring 1
force, Kg
 rate 1
Kg/mm
 spring 2
force, Kg
 rate 2
Kg/mm
1mm
 1.75
 1.75
 1.30
 1.30
2mm
 3.05
 1.53
 2.00
 1.00
3mm
 4.50
 1.50
 3.20
 1.07
4mm
 6.50
 1.63
 4.50
 1.13
5mm
 8.50
 1.70
 5.65
 1.13
6mm
 10.60
 1.76
 7.15
 1.19
Notes -
*Actual, in use spring  compression is about 3 to 4 mm total, with about .5 to1mm preload.
*Spring 1 has a rate of  about 1.65 Kg/mm, while Spring 2 has a rate of 1.14 Kg/mm.
*I was not happy with Spring 2 testing, alignment poor, probably Spring 2 rated slightly too low, maybe 1.3 Kg/mm more realistic.
*Springs came out of a Lamborghini that ran well, but was not checked with test equipment prior to Marelli disassembly for maintenance. The spring rates would be in the correct range, but the exact preload shimming is probably not correct for best performance.



P400 Parts List