spark plug questions

_kid_ · Post by **_kid_** » 31 Jan 2006, 01:14

Regarding my previous thread 'strange xantia today' im in the process of changing sparks and fuel filter.

Ive finally removed what seemed like the 'sealed for life' 6 screws for the coil pack off, now looking in there i require a long spark socket, im have the socket set, just need the deep tool, im going to gsf tomorrow, what should i be paying for the deep socket?

Secondly, i paid £2.94 per plug from gsf, they are part no N92722, why are they so expensive? (Relatively speaking for a plug)

Thirdly, as this is my first change which way do i unscrew the plug, from the engine

Many thanks

mezuk04 · Post by **mezuk04** » 31 Jan 2006, 08:19

£2.94 isnt expensive is it???

Glow plugs have the standard thread and i assume spark plugs to have them aswell, so anti-clockwise to undo, surely even Citroen cant mess that up

jeremy · Post by **jeremy** » 31 Jan 2006, 08:35

Have you looked at page 155 of the GSF on line catalogue? The tools they stock are listed there. I've never worked on a petrol Xantia but would expect to be able to undo the pligs with a deep socket of the correct size and an extension bar. All spark plugs (and 99.9% of other screws/bolts) undo anti-clockwise. (In fact about the only backhanded one i can think of is the small screw holding the chuck of my drill on)

Pheonix · Post by **Pheonix** » 31 Jan 2006, 11:16

I'm thinking about doing mine soon, so I hope the OP doesn't mind me tacking a question or two on the end.

You mention the price of the spark plugs - Is it worth getting more expensive ones, EG Bosch Super4 ones. Will they actually make any difference on a lower powered engine, for instance my 106, by saving fuel etc. Or are the manufacturers talking rubbish?

jeremy · Post by **jeremy** » 31 Jan 2006, 11:31

They probably won't make any difference on a high powered engine either. Yes you'll notice a difference if you replace worn out plugs with them but you'd probably have noticed the same if you'd fitted those recommended by the manufacturers.

If you use what the manufacturer of your car (not the plug) recommends you won't go far wrong.

After all - if you could get better fuel economy or performance the manufacturers would be fitting them as these things sell cars.

bxbodger · Post by **bxbodger** » 31 Jan 2006, 13:30

Bosch super 4 plugs won't make a noticeable difference to economy or power, but what they WILL do is outlast the engine........they are a good long term prospect because although dearer to buy initially they last a seriously long time, don't ever need regapping, and never seem to need cleaning either.

Because of the 4 electrodes they also seem more able to deal with a less than efficient or elderly ignition system as well.

They seem, in my experience, anyway, to be a more or less fit'n'forget spark plug.

dnsey · Post by **dnsey** » 31 Jan 2006, 17:48

Don't forget to gap the new plugs correctly, unless they're pre-gapped.

_kid_ · Post by **_kid_** » 31 Jan 2006, 18:45

dnsey wrote:Don't forget to gap the new plugs correctly, unless they're pre-gapped.

the ones ive brought are twin electorode, which according to haynes cant be adjusted, they are the ngk 'r' type. some info below

http://www.ngksparkplugs.com/techinfo/s ... country=US

rossnunn · Post by **rossnunn** » 31 Jan 2006, 18:51

I used a standard spark plug socket, with a 1/82 inch extension bar on, nothing flashy

dnsey · Post by **dnsey** » 31 Jan 2006, 19:51

I may be wrong, but I can't see why those plugs can't be gapped. Certainly the supression resistor (the 'R' in the name) won't affect this - although it may enable them to work with a larger gap.
NGK's FAQ here:
http://www.ngksparkplugs.com/techinfo/s ... country=US
certainly mentions nothing about it.

dnsey · Post by **dnsey** » 31 Jan 2006, 19:57

OTOH, if they're the side electrode type (what I meant by 'pre-gapped), they can't be gapped by conventional means.

alan s · Post by **alan s** » 31 Jan 2006, 20:00

If they're factory preset, I fail to see the advantage of stuffing around with them.
The theory of these plugs is that you can expect a spark every time and it will naturally jump to the closest earth, so if you have 4 to choose from, if one is set closer than the other 3, the spark will hit it more times than the others so the setting is no better than the closest one and having tried to set them in the past with no noticeable difference but almost sending myself insane in the process, I'd suggest you let sleeping dogs lie.

Alan S

dnsey · Post by **dnsey** » 31 Jan 2006, 20:16

The idea is to set the largest gap which fires reliably (and imposes no undue train on the ignition system). This results in better combustion, and reduaces the chances of fouling under adverse conditions.
Point taken re. the spark takng the lowest resistance path to earth, but under dynamic conditions, that may not be the closest electrode, and might well vary depending on the prevailing state of the combustion chamber on that stroke.

alan s · Post by **alan s** » 31 Jan 2006, 22:54

Granted, but if this is the case and given the micro seconds we're talking at higher revs, inconsistent settings must have some bearing on the overall running and destroy all the logic behind using them in the first place.
IIRC, the setting recommended is 1mm and this is also factory setting and as I said before, it's some fun job with a 4 pronger trying to get them right and if you screw up, besides risking damaging the new plug, you've got 16 of them to do all over again.

Alan S

Pheonix · Post by **Pheonix** » 31 Jan 2006, 23:09

Humm don't think I'll bother with the expensive ones then!!

I'll take an easily accessible one off soon to check it (I don't know when they were last done). Need to get some rubber tubing to fit over the end first though as recommended by Haynes. Don't want to cross thread the hole! The tubing is meant to stop you being able to screw them in crossthreaded, as the resistance is more than that holding the plug. Should be useful considering that they are a little awkward to get at.