Probably one of those 'How long is a piece of string?' questions... Anyhow, just for the sake of talking and assuming everything else is running properly, maintained correctly, car's driven sensibly - what sort of life expectancy would you probably see from a quality distributor rotor arm ie. Bosch? Are they one of those consumables that deteriorate through time even they're not used or don't cover many miles, or maybe putting the miles on helps keeps them in condition? Asking because I'm probably going to go back to the rev. limiting rotor that would've originally been in my car / distributor. Picked up 3 x old stock Bosch ones on the cheap, but ordinarily they seem to go for idiotic money, around the £80 quid mark assuming you can find them. Got to say however there's other decent brands also available, for much less money and better availability so it's only an issue if you just have to have Bosch. Question is then - should the three I have do me a (very) long time / lots of miles or am I tying myself into something that could prove expensive, ie. need changed every year or so - Yes, can always fall back to the solid rotor / rev. limiting relay I suppose... but aside from that it's just something that crossed my mind and am flapping my lips about it / interested to learn.
I don't see how a solid block of plastic with solid metal connection can degrade simply with time. They can with excessive heat become brittle. Corrosion or burn marks on the metal tip - that can be cleaned somewhat. However, sitting in a box in a 'cool dry place' they will be fine. I personally thought Beru was oem, and you can defo buy Beru. Worrying between Bosch v Beru is a bit too perfectionist really (imo)
well since dizzy is made by bosch, the original parts would be bosch, but beru are just as good. VW sell beru spark plugs as well as bosch, champion and ngk so definitly good enough quality. beru is what I mostly use anyway, bosch stuff for older cars can be extremely expensive these days
You read that many different things, for some reason 50K miles seems to be a common theme when you're Googling about when to change them, yet at the other end of the scale some claim it should be every time you do the plugs. Was just wondering what the 'official' line was and could maybe use it as a base line and tailor things to my own needs. Car's unlikely to being doing big miles and was reasoning (or maybe it was wishful thinking) that 3 x rotors would last me quite a while.
tbh nothing official I have seen just a case of pop cap off and inspect it and arm periodically then make a judgement call. as said they can get a bit pitted/blackened if you can smooth it off nicely with a bit of sandpaper then carry on. at the end of a day a spark is a spark, so if the car runs well then you have a good spark. if its missfiring, then you dont have a good spark and commence investigation till you find out why my cap and arm are probably around 10 years old, no problem. the other day I was troubleshooting a missfire, turned out the cap was cracked in half and rotor arm was a bit grotty. new cap, and cleaned up arm - problem not fixed. pulled each lead in turn, seems it was plug lead #4 all along, I could probably have put the cracked cap back on even
That's spot on, cheers... kinda confirms what I was starting to think. Probably continue with using the rev. limiting rotors, saying as I've now got them and they were so cheap. Didn't realise what they normally seem to go for and had wrongly assumed it'd be the cost effective option, rather than fork out £35+ quid for the rev limiting relay instead. I wonder how many MK1 owners out there have the solid rotor together with the non-limiting relay (or as you say the 7500 rpm one, that might as well be unlimited on an 8v) without realising it, it was all news to me 'till started looking into it?
That's a good point about the limiter arms, the limiter mech may wear out faster than the electrode. But again you'll soon know about it if limiter cuts in early or not at all Probably pretty common yeah, but tbh most 8v will struggle to rev up that high anyway and it's not like there are.any gains to be had up there on a standard lump
It looks like another clever bit of mechanical engineering by Bosch. Centrifugal force must push the connection contained in that off white plastic circular piece 'till it comes into contact with the metal tab. Not sure how that works, but does that tab then earth the rotor to the dizzy shaft and stop the spark? There's a tiny spring hidden beneath that regulates the moving piece, you can maybe just see the hooked end of it... amazing that they could reliably make it take effect at a pre-determined rpm.
yah sounds plausible, once earthed no more sparkies. i assumed the centrifugal force would just break the contact between central pin and rotor
