Are these spark plugs any use?

[D1 MAD]

A chap has posted the below details on the Celica GT4OC site, he has 500 sets of spark plugs to sell off that he believes fit early Rover V8's. Any one out there recognise the make / reference?
Could be a bargain, but only if they are any good.

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(hi gents ive cross referenced them they are eyquim sagem spark plugs the eyquem number is c32s that cross references to bp5hs for v8s before 76 and c32ls that cross references to bp5es v8 from 76-85)

[GreenV8S]

That's two grades hotter than the recommended plug. In any case I'd say that changing from NGK is something of a gamble, plugs aren't exactly a huge expense and personally I wouldn't want to take the risk - that's having gone through probably a dozen sets last year.

[D1 MAD]

Thanks for that. I certainly wouldn't risk my engine for the sake of saving a few pounds on plugs.

Whilst talking plugs I've heard of people experimenting with changing plugs to a grade 'hotter' or 'softer'. Can anyone give a brief description of what effects this actually has and the reasons / possible benefits for doing it?
This is one of many empty voids in my automotive brain cell allocation space.

[GreenV8S]

D1 MAD said:

changing plugs to a grade 'hotter' or 'softer' ... what effects this actually has and the reasons / possible benefits for doing it?

Spark plugs are designed to operate within a certain temperature range. Too hot and they can cause detonation, too cold and they won't self-clean and will foul up and not spark properly. This range is the same for all engines and plugs. The operating temperature that the plugs actually run at in a given engine is a balance between the amount of heat going into the 'hot' end of the plug versus the amount of heat being conducted way by the body of the plug. The amount of heat going in varies depending on lots of things like the compression ratio, fuel mixture, throttle and revs. The amount of heat being conducted away is determined by the construction of the plug.

The normal plug grading system uses a number to indicate how much cooling the plug provides. The higher the number the more cooling i.e. the cooler the plug will run in a given engine. If the plug is fouling up then you would go for a hotter plug (smaller number). If it is burning up or you are getting detonation you would go for a cooler plug (higher number). The aim is to choose a plug which conducts away the right amount of heat to stay within the optimal temperature range for your particular engine driven the way you drive it.

[Boosted Ls1]

Don't forget that some whilst manufactures use a low number to indicate hot, brand X may do it the opposite way round.

Boosted.

[Mark Adams]

NGK have an exceptionally usefull website, with full cross reference facility. There's also lots of great info about plugs on there. You can find it on:

www.ngkntk.co.uk/

[TOPTON]

So which plugs to use on a 350SE 3.9 engine?. Wedge pages suggest BPR6ES and thats what I fitted. Recent pages have suggested BPR7 and NGK page says BPR5E for the 350i.

Almost as bad as trying to choose wallpaper!!!!!!!

[pwd95]

Mark Adams said:

NGK have an exceptionally usefull website, with full cross reference facility. There's also lots of great info about plugs on there. You can find it on: www.ngkntk.co.uk/

[dickymint]

TOPTON said:

So which plugs to use on a 350SE 3.9 engine?. Wedge pages suggest BPR6ES and thats what I fitted. Recent pages have suggested BPR7 and NGK page says BPR5E for the 350i. Almost as bad as trying to choose wallpaper!!!!!!!

Most people would agree that NGK B7ECS are the "preffered choice" as per Bible.