Hopefully the more mechanically knowledgeable members will be able to answer what the 206/ 246 section could not. Does any one know if the distributor springs for the weights should come in matching pairs.If you look at post 251 in this thread http://www.ferrarichat.com/forum/308-328/105874-1979-308-gt4-13.html on a 308 it seems not for the shorter springs.My distributor I believe is a Magneti Marelli S125 bx-15 distributor I have 2 springs at 14mm long,1 at 16.5mm and 1 at 18 mm.
Never bothered to catalog it but there are several different spring configurations for the various Marelli distributors. When you run into a set that have been poorly serviced in their history you can spend a great deal of time in front of a distributor machine sorting it out. One reason I never give estimates on distributor work. So few have been properly looked after headaches are the norm. There will probably be deep and shallow spring pockets. The 14's will go in the shallow pockets. The 18 and the 16.5 will go in the deep pockets. If the pockets are the same depth you're screwed. Trying to service these without a machine is really an exercise in futility. By this point in their life it is really uncommon not to have advance issues, worn out parts etc.
^ This. These springs also vary by spring rate as well and are tremendously stiff. Considering their small size, I've measured them from as low as 38 lbs (14.5mm long) up to 208 lbs (16mm long)! Different rates allow the weights to move out faster or slower depending on the curve (usually the lighter springs will be used during the first phase of movement to quicken the rate, then the heavier springs take over and keep it steady for the remainder of the curve).
Thanks for the replies,but I am a bit concerned about buying new weights and springs which do come in matching pairs if that is not what the distributor originally had.I know its all about getting the advance curve right, but I often find re manufactured items are inadequate in some way.
I bought a new set of springs and weights thinking they would be a straight swap for the old but the springs were way too stiff. In the end the old springs and weights were re-used and the curve was & is perfect. In fact if you want my new unused set, let me know but I haven't really sold them very well
Thank you Andy for your kind offer.I would like to find out the correct spring spec first before trying different springs though.
This might be some help. Once you check the tension weight and the height of the springs this illustration shows the clearance between the different springs and the RPM ranges they effect. Note that two sets of springs are removed in this illustration. Hope it helps, please report your findings. Image Unavailable, Please Login
