308 GT4 Twin Coil Rotor arm repeated breakages

I had a brand new 328 doing that back in 1986. Exact scenario, every time the owner ran up the rpm another rotor would break. Turned out to be loose cam bearing caps allowing contact between cap and rotor. Only happened at high RPM.

Your car has a real distributor so it is very different. Be sure the distributor bearings are good and there is no end float in the upper shaft. I would also be sure there is not some mismatch of cap and rotor.

 

There is a lot of confusion with rotors and to what cars they fit. In the original parts sometimes just very minor dimensional differences were present, but anyone just looking at them will not notice that they are different. AND: all independent suppliers copy and paste application information from each other and misinformation is distributed thereby.

As an example, that I positively know, because I own both cars since long. Suppliers offer the same rotor as a fit for Alfa Montreal and Lamborghini 12 cyl. This is definitely not true. They look identical, but by checking one will note that the contacts of a Monti rotor are slightly shorter than those of the Lambo rotor, because the contacts in the Monti cap are arranged on slightly smaller circles.

The Monti rotor will work in the Lambo distributor, although the gap between rotor contacts and cap contacts will be too large. Not well running engine will be the "worst case".

The Lambo rotor will presumably (I did not try it out) not work in the Monti, because the gap may be not present.

So although all suppliers (!) claim that the same (identical) rotor fits both engines, this is clearly NOT correct. But in internet age, if enough people state a wrong thing, then it will become correct with time, so have hope .

Maybe there is a similar issue with the suppliers of your rotors, in particular if it is a reproduction ....

Rifledriver, if the top bearing of the distributor is so worn that the rotor contact (of a correct rotor!) touches the cap contacts, then I would assume that the distributor will be quite noisy at any rpm. I never encountered distributor bearings so excessively worn (but who knows , maybe a combination of slightly wrong rotor geometry and slightly worn bearing is the actual fault).

P.S.: In my example, unfortunately the rotors offered fit the Monti (and not the Lambo). It would be preferably the other way around, since with a (correct) Lambo rotor the contacts could easily be filed down to the correct Monti dimensions. You might be in the lucky situation, that the rotors supplied to you are a little bit too large and just need slight filing off. Anyway, you should try to get the correct rotor dimensions by inspection of a nos part or from someone, who still drives the factory original rotor. Do not believe anything else .... .

P.P.S.: Suppliers even manage to offer (and sell?) products for not existing cars. E.g. look at the ignition wire sets for Jarama and Espada. All suppliers give you the choice "single distributor" or "two distributors" *loooool*.

P.P.P.S.: And if you believe I am bashing independent suppliers, take this: If I ordered a Jarama rotor from the factory, they will presumably send one fitting a LM002, but that, at least, is a quite obvious mismatch ... .