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View Full Version : How often do you change Spark Plugs?



53catalina
02-07-13, 08:05 PM
Just realised I haven't changed mine for about 8 years.
Probably covered about 12,000 miles in that period, and I think they are still ok.
They do get gapped yearly and all look ok, but I was just thinking should I put in a new set after this time?

Mark
02-07-13, 08:14 PM
I change mine every 4k , don't know why I just do along with oil and filter .

I do cover around 4-5 k a year so do it annually , I have changed my cap and rotor after 4k as well . It's cheap to do so y not ;)

stretch
02-07-13, 08:16 PM
i had the same thought a couple of weeks ago,been in 6 years took them out they were fine on appearance,car always starts never misses a beat fires up straite away, so i thought fuck it,n put em back in

moparhemi345
02-07-13, 08:22 PM
Factory says 30,000 but I do em on 50.000.
No clean/gap malarky just bung in new ones.

stilltrying
02-07-13, 08:54 PM
I change mine every 4k , don't know why I just do along with oil and filter .

Ok if you only do 1K a year I suppose but a bit extreme if you do 12K a year. Some of the newer engines have plugs that only get changed after 50K and I believe one lot even say first service at 100K!!!!!! but can't see that working to be honest.

roscobbc
03-07-13, 12:52 AM
Seem to be changing mine every year - with a bit of a cam and 4 corner idle adjustment it likes a rich mixture to idle well - downside is, and despite and MSD ignition two or three plugs tend to give-up from too much carbon build-up - gone now up a heat range from NGK BCP7ES to BCP6ES and weaked-off the idle a bit,

Chunky
03-07-13, 08:22 AM
I'd do them when they need changing. There's no point throwing away good plugs just because a manual says so. Just check the condition and be guided by what you see.

I'm not generalising when I say that a lot of mechanics these days are fitters who do what the manual or the computer read out says rather than using their skills to identify a problem and fix it. They seem to just swop things in the hope that it will fix a problem. IMO

vinnythespud
03-07-13, 09:48 AM
i think its a good idea to fit them once a year in old engines,the modern fuel injected engines will probably be ok with the 45000 mile intervals but its unrealistic to expect a 1960's carb fed engine to do the same,some maufacturers recomend 100,000 miles. i bet it would be a right laugh trying to get the plugs out after that long

B-17
22-09-13, 08:01 AM
I whip them out a couple of times a year clean/brush them up regap bung in and away, if it fires up good and your ear says its good c
Keep them in.

If I have a firing running problem once I have put it right - including a new spare plug set in - I bung on the old ones back on and so far it's worked for me, had my ones in nearly three years.

Plumpcars
22-09-13, 08:19 AM
40 years back a plug was changed on a quality car every 10,000 miles. They generally showed wear at that mileage. As technology moved on that mileage span increased. Use and engine condition have a major bearing on things.

SG57
22-09-13, 08:43 AM
When I first got a Nitrous Fogger system and until we got things like a retarder set up I sometimes used 4 or 5 plugs in a 1/4 mile.....LOL
Not much use in this thread but it brought back memories about what amateurs we were.

Rog.

brizey
22-09-13, 11:21 AM
Earlier this year I changed the plugs in my Flathead roadster after 13 years of abuse during which time all I`d done was a yearly clean and gap. They were all in as new condition still but I thought it was about time as I`d had my moneys worth from them!.

As an aside, my mum used to work at Champion Spark Plugs in the `60s when their factory was at Hatton Cross (Heathrow) and we kids used to get taken round on open day tours which included all the top (F1 and other type) race cars of the day doted about the factory floor. My mum used to operate a `tamping` machine which cemented the centre electrode into the plug body, a pretty boring job by all account...

Plumpcars
22-09-13, 12:16 PM
Crikey Brizey. I spent some time training there in the early seventies!

cptpugwash
22-09-13, 09:50 PM
When I first got a Nitrous Fogger system and until we got things like a retarder set up I sometimes used 4 or 5 plugs in a 1/4 mile.....LOL
Not much use in this thread but it brought back memories about what amateurs we were.

Rog.

we used to cut the ends of the earth straps off (think thats what they are called) fiddley old job
they used to melt off else

Fordson Van
05-10-13, 06:25 PM
Modern engines in modern cars will easily stretch to 40,000 miles but in a "hotrod" where generally the fuel mixture can run lean without the engine complaining or showing signs of a lean mixture the plug can overheat and breakdown the amalgam properties of the copper core. The electrode tip can look as new but the resistance of the core is compromised and leads to high speed misfire and sometimes poor flame propagation resulting in reduced fuel economy and power. I worked at Toyota in the 70s when we experimented with lean burn engines and found that plugs would turn light green at the tip when run too lean. This was due to the copper core braking down and gravitating to the electrode causing misfires and poor starting when hot which is sometimes a symptom of hot running V8s

cptpugwash
05-10-13, 08:11 PM
whats amalgam mean :beuj:

Fordson Van
05-10-13, 08:26 PM
whats amalgam mean :beuj: Its the mix of metals found in low composite copper usually only containing a maximum of 30 percent pure copper,the other metals include zinc and brass. The residual metals contained in the spark plug core bleed down towards the electrode end preventing secure earthing of the current :)

cptpugwash
05-10-13, 08:45 PM
thats all gone way over my head

sounds good though :)