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By Flintstone
Do people not anneal spark plug washers before re-use these days? Used to be one of my favourite jobs with a blow-torch and tub of water.
By cockney steve

In over 57 years of playing, tinkering, repairing and servicing IC engines, from the 16:1 two-strokes (1/2 pint oil to 1 Gall. petrol ) to Jaguar E-types, Lancia Beta Volumex (supercharged) I never remember annealing a plug-washer after finding that there appeared to be absolutely no advantage.

The ancient 2-strokes oiled-up frequently. washers were never solid copper, more a swaged-over hollow "eyelet" tighten to contact, then add 1/3 -turn.....when they're flattened, the "nip" is somewhat less.

Now, before someone hysterically screams that in an aero-engine, this would mean the plug would sit too far in the cylinder-head, moving the electrodes a few thou' from the ideal combustion-initiation centre BUNKUM ! Now prove to me , that every new plug, every cylinder-head, has threads aligned so a "text-book " installation will always see the side-electrode in the same radial- alignment and not blocking the gas-flow of the charge, between the electrodes.

No, thought not!

55years a motorcyclist, almost 20 as a garage mechanic, worked on marine and agricultural

replaced hundreds , perhaps thousands of spark-plugs . had a broken insulator-nose in a company -car
(installed by the manufacturer) installed a set of "Lodge" in nan Audi 100 and the centre electrode arc-deposited it's tip on the shell and side-electrode. never had one leaking or loosening through faulty installation.

tin hat on, your turn, who's going to prove this heretic is wrong? :twisted:
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By Rob L
Flying_john wrote:Yes, to cherry red then into the pickling solution to clean them up.

I'm sure you mean to anneal them.

To Flintstone: yes I do exactly what you do. I normally wait 'til I have a few tens of them, then heat them up and then quench.

They don't cost a fortune individually, but with the $ rate so poor, they are eminently re-usable.

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By Flying_john
I'm sure you mean to anneal them.

Yup - Cherry red then quench and pickle at the same time, weak acid solution gets rid of the black and does the quench at the same time.

I have only ever seen solid copper aviation plug washers, I think Steve has used a variety of other types in the automotive business, but only ever solid soft copper in Lycosaurus and Continentals.

The depth and orientation inside the cylinder is not important because of the double (sometimes triple) electrode and the depth almost irrelevant (although no fitting long reach varients into short reach holes !)

Drop of your graphite goo on the threads (except to the two nearest the end thats going in the cylinder) and roberts yer mothers brother.
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By Flintstone
I dunno. I just recall that as the spanner monkey's assistant trainee apprentice bottom knocker, and a pilot to boot, I was always given the job. I thought it was purely to soften them, hadn't thought the fickness came into it.
User avatar
By Sooty25
What is one supposed to do with CHT sensor washers that sit between plug and head?
By cockney steve
^^^^^^^^ There, @Sooty25 has the nub of the whole debate.
I might have read about a Rotax installation, but the thread went into all sorts of arcane theorising about CHT sensors altering the depth of plug entry and some respondents advocated removing the plug-washer.

Rotax use (almost) standard spark-plugs. I say "almost", because the little screw-terminal on top is replaced by a 1-piece terminal-post of exactly the same profile......a good excuse to fleece the victim of another couple of quid, with the specious argument that the plug-cap is such a poor fit it will allow an ordinary terminal to unscrew and the cap will fall-off with the terminal inside it,
Apparently many owners substitute a different type of plug (Iridium, IIRC) which is of surface-discharge construction and much less prone to fouling.

I theorise that you can partiallly remove a screw-terminal and put a crimp in with pincers...that will make the threads nip. alternatively, just nip the thing tight with a pair of pliers.....for the truly anal, a spot of loctite secures the terminal.

Now, the interesting issue to this marketing "scam"....NGK apparently refuse to sell the removeable-terminal plug for Aviation use, in spite of Rotax having sold the engines with "not for aviation use" plastered all over! So, you go to a motorcycle dealer and get the cheaper one!

To get back to the core question. Anyone who has worked with copper, including plumbers and electricians) knows it work-hardens. but a single twisting of strands of wire, does not render it hard. likewise, logic dictates (remember, both the cylinder-head and the plug have machined faces) that a washer can be tightened several times before work- hardening makes deformation difficult.....but a gas-tight seal will ensue before that stage is reached anyway.

Flexy brake-hoses are fitted with solid copper washers, reused them if not damaged, never annealed, never had a leaker and never had to overtighten to the point where threads start distorting

(I cringe when tyre fitters use a "buzz-gun," changing wheels and leaving customers with stretched wheel bolts that won't budge when they get a flat tyre next.@Flying_john .....Presuming the incoming gas-charge flows across the plug-electrodes in the same orientation, then a side-electrode directly in the path will tend
to split the flow away from the spark-gap....otoh, if 2 of a triple-electrode design are either side of the gas-flow, they could be held to channel the charge in to the spark-gap......but, of course it's all bunkum because the combustion chamber is designed to make a turbulent charge for thorough mixing and an even burn. Likewise, a few thou different depth of a CHT sensor-washer, or a re-used plug washer is probably less than the difference in placement that worn electrodes will make to the plug-gap.

Marketing scaremongering at it's finest :twisted:
User avatar
By Lerk
I always thought that to anneal you has to let it cools slowly - without quenching.

By cooling quickly you harden the metal.
Last edited by Lerk on Sun Feb 10, 2019 6:59 pm, edited 1 time in total.
By tankbarrell
With copper it makes no real difference. The only reason to quench copper is to cool them quickly and it helps to release the scale. Steel alloys will harden when quenched.
User avatar
By Lerk
I’ve never bothered to quench when I’ve done copper but always assumed that it would be she same - but of course there is no carbon to worry about!
By cockney steve
Ferrous;- to anneal, cool slowly. to harden, quench rapidly (oil is preferable to water for tools etc. Horseshoes, -other non-precision stuff water is temper hardened steel clean off scale etc to bright metal, immerse in a bath of sand, preferably with a long side having a visible strip from end-to end......heat and watch the colours run when the metal reaches the desired colour, remove rapidly and again quench.

Non- ferrous;- to anneal heat evenly...copper can be red hot, but alloys such as brass or aluminium will melt first! old dodge...a piece of a bar of ordinary household soap will draw a mark on most alloys. When the mark goes brown, quench as quickly as possible. the metal will be soft. if drawing-out alloys, they'll work- harden and need periodic re- annealing. Some alloys are prone to cracking working them whilst still hot enough to anneal, usually works......let them cool slowly and the hardness will largely be retained.
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