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Reading spark plugs - when to change

Big Red VF-SII Go-kart

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I don't worry about fuel economy ;)

I do!
I'm a bit panicked by this figure. Going to bring it down to the holy grail of 3.9L soon. (Still, this was from headbutting a headwind for 72km, so still reasonable).

20201119_114138.jpg
 

07GTS

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Yup. I get my plugs from the US at us$1.28 each. I buy multiple sets . I had iridium But I dont think more boost agreed with em. I was running 1 step colder but going to try 2 steps cooler next...
u running ethanol or just petrol ? if ur petrol id go a 7 or 8 heat range (depending on boost) but ethanol can stay a step colder as it absorbs more heat when ignited, i found the 6 range was good to 14psi on ethanol with 1mm gap, ran couple more psi seemed to like .8 gap better, thats a good price on plugs
 

Immortality

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Sorry, $1.82

Just 98, currently running autolite 605 which is the equivalent to NGK 7 heat range. Got a set of 604's which is an 8 heat range. Currently Running about .050" gap on about 12 to 13psi.
 

VFSV6FORME

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Ac Delco plugs. Just pulled one to check the condition.

Car's done just under 50 000km
Original engine was replaced at 35 000 km.

1. Do these look like 50 000 or 15 000km plugs ? i.e. did Holden reuse original plugs on new motor.

2. What do they tell you about how the engine is running ?

3. Are they still good ? I.e. no need replace.

Would love to hear some thoughts :)

To me they look like original plugs and it appears there is some carbon buildup on them. i.e. running a bit rich.

However, they dont look like they need to be changed yet.
If I was you I would replace them because you have taken them out not unless you are short of $$$. For me replace them.
 

the_boozer

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If I was you I would replace them because you have taken them out not unless you are short of $$$. For me replace them.
You don't think he put the plug back in straight after the photo and is driving on it today?
 

BILL POP

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They are old std plugs. Does not apply to the iridium style plugs
 

Simmo68

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Here they are...
These are mine at 108000k's, as you can see the centre electrode is worn away.
Definitely replaced them with new plugs and leads.
 

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