OEM self-limiting rotor buttons, pros and cons

Saloons
1

So I will dig up my box of “ignition parts”, someone has moved then about, but I believe I may have a number of NOS “self-limiting” rotor buttons , as pictured below

420G rotor button
420G rotor button480×640 50.5 KB

They are ex-dealer stock, they may be NLA these days ?

I ran the same one for 20 years in my 420G never gave me any trouble

New rotor buttons are of unknown quality , with inferior plastic, metal and rivets

I cannot recall if peoples opinion on them is that these are very high quality, or gave some problem with cutting out ?

I suspect they would not have degraded much over the years despite being NOS ?

fit MKX/420G/E-type/XJ6

all info welcome

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My opinion is that they’re excellent, don’t ever throw them out throw them my way! I think mine is fit for twenty years though. I believe I only found very few NOS units back then, ended up with a cheap new one for emergencies but will I ever need a spare, probably not.

Never reached the limit so no clue how accurate the springs are and what it feels like. Anyone?

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At what distributor speed or engine speed are these set to? As to regular distributor rotors the red ones supplied by Distributor Doctor, and now Moss, are apparently reliable and do not short out like some of the earlier (non Lucas) black after market ones. I had two failures in my 3.8S before learning of this defect.

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There‘s a number stamped into the brass, that’s the rpm it is supposed to limit at. X2 for engine rpm, I‘ll look for a picture.

I remembered that there was an issue with the new things, and then I saw this and remembered that my distributor is smarter than me

Here’s an example, 5400 rpm. I think they were used on the 4.2 with BW8 because the torque converter wasn’t strong enough for more?

Forgot the example :face_with_raised_eyebrow: just google DRB111, my example was stamped „2700“

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Thx David,

I am presently going through my 420G spare parts collection, organising and photographing them.

If I find a better part than is on my car, I install it, which is fun.

It was excellent to find an NOS rear chrome plinth, which looking disgusting, as it was covered with cosmolene and dirt, I thought it was no good at all, but once cleaned and polished, it had no mazak blooms at all.

I also have at least 10 of these plinths in a box, and this was by far the best

I like to retain at least one good spare but the rest I will probably offer for sale, its not much good to me having twenty rotors in a box

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