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PaulAA

Spark plugs for the six-pot

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Chaps

What is current wisdom for spark plugs for the 2.5 six-pot with carbs?

Champion N9YC?

NGK BP6ES?

A N Other?

Paul

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Used the NGK BP6ES on the GT6, and now after the fast road conversion the BP7ES.

Works fine.

Martin

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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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Thanks for the feedback and thanks for the links, Phil & Hamish - Bosch triple cores now ordered.

Cheers

Paul

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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

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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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If all is working well then I'd probably leave them alone (not very easy to adjust/measure anyway), but if you find you have a high rpm misfire, then 0.025 - 0.030 sounds good.

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1 hour ago, Nick Jones said:

but if you find you have a high rpm misfire,

I might find out this weekend at Prescott if the red mist comes down!.

No rev limiter on mine, other than my right foot.

Ian

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