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Spark plugs for the six-pot


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NGK BP6ES seem to be the normal go-to. Personally I like the 3 prong (or now easier-to-find 4 prong) Bosch ones - the Triumph engines love them.  W7DTC are the non-resistive 3 prong ones or WR7DTC for the resistive.

These may be hard to find now, esp. the non-resistive.  The number of prongs is probably largely irrelevant (though extends life), it's being a side-electrode design with the spark exposed to the chamber that I think makes them work better.

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I'm with Nick and Alan on this, triumph engines love the multi-prong plugs!

I stocked up on these the other year, so as to have a decent supply, eBay is your friend for these (this is who I used previously, they sell in other quantities as well)

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F232610894050

Cheers,

Phil

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  • 3 weeks later...

You can use wire gauges, small drill bits or the special tools that look like a selection of small radiator bleed screw keys - the business end being a short length of tube that fits over the central electrode and whose wall thickness defines the gap.

It is quite true they do come preset, but usually at 0.040” which is fine for coil pack ignitions and even decent conventional electronic ignition, but is pushing it for points ignitions.

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45 minutes ago, PaulAA said:

A small question from the hand of the dim-witted... how do you gap these 'ere three-pronged plugs?  Do you bend the feeler gauge..?

Paul

Mount plug in lathe chuck, centralise using dial indicator, and then do the same to central electrode.    A fine punch and small hammer are useful.

  Fiddly job, but so effective!    The spark doesn't know which way to go, so goes three ways at once!  Result - megaspark and MUCH more power!

John

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55 minutes ago, JohnD said:

The spark doesn't know which way to go, so goes three ways at once!

Does that happen?  I would think that you'd only get one spark between the central electrode and one of the prongs, it'll probably switch around as they fluff up and wear though.  As I understand it the advantage is more that the spark is not shielded from the combustion chamber?

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1 hour ago, JohnD said:

 

    The spark doesn't know which way to go, so goes three ways at once!  

John

Come on John,  You can only do that if there is an Interocitor fitted.

The spark goes to one electrode at a time - path of least resistance.

 

Roger

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No, no!   Didn't we have PeterC on here recently about the two-slit experiment?       It's quantum physics  (a doddle compared to rocket science), and the electron or photon  goes through BOTH slits at once.     And, in this case the spark goes to ALL the  electrodes at once.   But it's essential that the gaps between them and the central electrode are all the same, else the wave function collapses and only one slit/electrode transmits.    Hence the need, delicately and carefully and with a dial indicator for maximum accuracy, to use a hammer to bend the central electrode so the gaps are identical.

John

 

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21 hours ago, JohnD said:

It's quantum physics  (a doddle compared to rocket science), and the electron or photon  goes through BOTH slits at once.     And, in this case the spark goes to ALL the  electrodes at once.

Actually, yes, this is right.  It's only when you observe the spark that the wave function collapses and it 'picks' an electrode at random, under normal operation and hidden from observation it'll be definitely going to both all the electrodes and none of them at the same time.  

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Absolutely, and the risk with these multi-electrode spark plugs is quantum entanglement.  If your dizzie starts to suffer from entanglement then the spark may not only go to all electrodes in that plug, but to any of the plugs!     This quantum non-locality will make ignition timing very difficult to achieve.

John        

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On ‎5‎/‎3‎/‎2019 at 2:14 PM, Nick Jones said:

It is quite true they do come preset, but usually at 0.040” which is fine for coil pack ignitions and even decent conventional electronic ignition, but is pushing it for points ignitions.

Nick

What gap would you suggest for points (0.025"-0.030").

(I have a set of these now, but just wacked em in!......car seems to like them!)

Ian

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  • 2 weeks later...
On 5/3/2019 at 6:55 PM, JohnD said:

No, no!   Didn't we have PeterC on here recently about the two-slit experiment?       It's quantum physics  (a doddle compared to rocket science), and the electron or photon  goes through BOTH slits at once.     And, in this case the spark goes to ALL the  electrodes at once.   But it's essential that the gaps between them and the central electrode are all the same, else the wave function collapses and only one slit/electrode transmits.    Hence the need, delicately and carefully and with a dial indicator for maximum accuracy, to use a hammer to bend the central electrode so the gaps are identical.

John

 

John, Much as I love the two slit expt, and entanglement ( and much else I dont understand) I think the spark takes the easiest route of the three but that can cnange spark to spark. Turbulence at the gaps will differ compression to compression quite markedly. Having three gaps to choose form enables the spark to ignite the best gap-local mixture. I think. That reduces "cyclic variability" in flame spread and improves power.  More here in my 2016 talk at IWE:

https://supertrarged.wordpress.com/

But as you say all the gaps need to be set equal.

Peter

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I shouldn't show you this, but in doing so you are automatically sworn to the Offical Secrets Act, 1989, with all that that implies, so if you do not intend to comply, despite the santions that that MI6 can within that Act,  employ, do NOT read on!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A precisely similar gap between several electrodes can, as demonstrated above, lead to a quantum entanglement so that they all transmit the spark simultaneously.   So what if there are even more electrodes and a constantly varying gap?    Eh?     Think on't!    The inclusion of  a time variable  introduces imaginary time into the equation for the wavee function, stabilising it to an axis running perpendicular to normal time, so that the spark can transmit at any time, ensuring that it does so at the optimum time.      Perfect ignition timing is thus assured.

Just as the axis of imaginary time is at right angle to that of normal time, the spark plug that achieves that has an axle perpendicular to the electrodes!     Thus!   You DIDN'T hear it here!

J.

Flame spinning Electrode Spark plug.jpg

Edited by JohnD
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