V12 dist cap/rotor

Martin I changed mine last year and both where also in a terrible state even worse than yours and to top it all they where date stamped 1991. Could they be the original ones My car has dealer history so yet another example if the poor service from the stealers

It ran like a dream once they were renewed

I changed mine last year and they where worse than yours.
I also changed the plug leads and the coils.

Expect much better MPG now.
And I would reccomend changing the plug leads too.

Chaps, did you get the caps/rotors from BMW? They look pricey on realoem etc....? I bought used HT leads from eBay as they were an absolute fortune OEM, can you get aftermarket leads? You're probably all feeling sorry for me and thinking of sending me a food parcel for xmas

Used plug leads!! That really is risky, not because they may not be good now but how long will they last? Magnecor have a choice of 3 lead sets for the 850, better than OEM 7mm, high performance 8mm and race spec 8.5mm, all cheaper than OEM and all warranted for 10 years.

German and Swedish (GSF car parts) have the caps and rotors at a good price as they are the same as a 325i.

Great thanks. I saw the 8mm ones on europerformance.co.uk for £177.95 is that any good?

Zitat von NickF;57532

Great thanks. I saw the 8mm ones on europerformance.co.uk for £177.95 is that any good?

I can beat that price. And I have them in stock. They will have at least a 14 day lead time.

Zitat von martinw;57534

Nick,
Got my caps and rotors (and the plugs) from Eurocarparts.
£96 for 2x caps and rotors and £22 for the plugs.

If you're worried about the caps and rotors being non-original - don't be.
Although for these Euro did not list the brand (unusual, as they do for most parts), when they arrived, they were Bremi brand. Exactly the same as my originals.
And the caps even come with the plastic outer cover and the fixing bolts (look exactly like the originals).

They have an internet site where you can check prices, choice of brand and availability.
They also have a lot of local shops in UK (same prices and they probably have a shop near you) where you can order and inspect the parts in person when they arrive. No delivery charge. Don't like them - no problem, they just send them back to the central warehouse.
Better than paying for return delivery for unwanted items off most Internet sites.......
No connection etc etc

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I concurr with that. Euro car Parts are another good supplier of these parts.

Thanks chaps. I have a euro car parts very close to work so I'll check it out at lunchtime (assuming they're open today). 8Tech - I'll go for a set of leads from you, let me know how much to pay you. Cheers, Nick

8Tech,

I was wondering about the plug leads: What's the difference in 7mm vs 8mm? What benefit is there to go to 8mm?

really curious..

I expect someone far more knowledgeable about such things will be along in a minute to give you a proper answer Fuzzi, just a layman's view though, the increase in diameter will give a significant increase in overall internal surface area - maybe that means significantly more conductivity? Just guessing..

yep - found an answer on the magnecor website:

Zitat

If you don't intend to upgrade your vehicle's original ignition with a high-output ignition, you may not need larger size wires. Magnecor KV85 and R-100 Race Wires have been designed primarily for race engines that will be run with high-output ignition systems, and contain high-capacity 2.5mm conductors that require extra insulation when used with extreme-output ignition systems. Magnecor Race Wires will also be exposed to heat an unmodified production vehicle will never experience. However, the major advantage Magnecor Race Wires have over conventional 5mm, 7mm and 8mm wires is that neither the high-capacity conductor nor the insulating jacket will wear out during the life of the engine.

also, this is an interesting (albeit trivial) statement about horsepower-gain:

Zitat

Despite what is published in advertisements and some vested interest magazine articles, no spark plug wires will generate or "install" additional horsepower. However, a decrease in horsepower will occur if the wires' conductors fail to conduct the spark energy needed to fire spark plug gaps, or EMI emitted from spark plug wires causes the engine management computer to react abnormally, or so much spark energy is lost into the ground straps of so-called "built-in capacitor" wires that little is left to fire the spark plug gaps —see test in Circle Track Magazine (USA), May, 1996 issue. For these reasons, Magnecor Race Wires are used by many successful race teams and individuals all over the world to eliminate the risk of such events occurring.

so, as far as my standard engine is concerned: the 8mm will yield no gain, whatsoever.

Leaves one question: What's the average life span of OEM plug wires?

I'll definetely go for Magnecor, at the end of the winter. They seem to know what they're doing and they're cheap. It's just, that I'll probably not go for the 8mm - unless, of course, some other good reason for 8mm comes up, here..

Well as an electrician I can only say that the bigger the wire, the less the internal resistance is.
Put short, that is why a thin wire will burn off/melt the insulation if the power is high enough.

An old wire will have some degree of corrosion to it no matter what.
This again increases the resistance.
resulting in a weaker spark, causing an poorer combustion, poorer consumption and sot to form on the valves.

I replaced my wires last year with new "oem", BMW dont have tham made anymore, but the ones I got was from the same vendor that made them for BMW, acutally bougt them from Gault in NY, and BMW dealer.

My car then got a better idle, the consumption dropped, and the engine responded better and felt more powerful.
I did also replace the coils and the rotors/distributor caps and installed new 4 electrode spark plugs at the same time.
All the parts I replaced where 17 years old at the time (exept for the plugs).