Technical The Spark Plugs

[Mike1alike]

So, I have the M12 diameter spark plugs on the mk2 Punto 1.2 8V 188 engine.
I found out the original plug code no. is 55188857. That is 0.8 mm gap.
I just bought new NGK spark plugs, the NGK 4983 DCPR7E-N-10. But these are 1.0 mm gaped.
Should I use them as they are or should I modify the gap to 0.8 mm.
I used the NGK before, it's not the first time I bought them and they are good quality. Usually, I just put them as they come, 1.0 mm gap. I would do the same again.
Is it good? Is it bad?

 

[AnthonyH]

I think you should use them as they are. Many years ago the gap did matter, but no longer.

 

[Mike1alike]

I agree with using them as they are.
As for gap doesn't matter any more, that's the simplest way to say it and I think there is more to it.
I don't know about other brands, didn't check their gap.
I'll say about the NGK though. I noticed that prior to the DCPR7E-N-10 (NGK 4983) they've had the DCPR7E, NGK 3932. And the gap on that was 0.8 mm. The NGK 4983 is considered an improvement to the prior, found something like "Constructed for longer life and optimum performance. Trivalent metal plating provides superior anti-corrosion and anti-seizing properties". And the gap is 1.0 mm on this one. Although I didn't find any mention on how did they get to larger gap, I think probably in their testing the results were the 1.0 mm gap works the best.

 

[AnthonyH]

There will be a difference, yes, when it comes to gaps, but its quite small in comparison to the main issue. The main issue being whether to buy plugs in copper, platinum or Iridium.

 

[Mike1alike]

Well yes, that too.
I bought them in platinum. I'm satisfied with them. Good quality and pretty good price.
And then, talking of issues, there comes the talk about torque. Multiple sources give 25 Nm but I think that wrong number comes from the other type, the M14 diameter plugs fitted in other engine models.
This NGK 4983 gives the correct torque in the technical specifications. It says 10.8-14.5 lb-ft (14.64-19.65 Nm) for the aluminum CH. I crossed that with data from eLearn, but there are multiple values. I did them 18 Nm although eLearn does not have the 1.2 8V engine listed at 18 - another mistake. Of course, you can always tighten them right using just a normal ratchet. Just having a torque wrench, I did it that way.

 

[GrandePunto PL]

This is well(?) known error in the eLearn, torque for M12 sparkplugs is wrong (too high, it's a value for M14, numbers above 20 Nm = 2.0 daNm).

Same for engine mounts in some models (new Tipo - value for M8 is for bigger bolts, M10 and some folks will "pull" the threads, rip them out).