spark plug gap

[renxun]

what are the supposed spark plug gap in a 1jz...? i supposed there is a specific one.... but i dont do any gap adjustment... just buy fresh plugs and dump in.

anyone actually gap their plug out of the manufacturer recomendation.? if yes why?

[Draven]

Depends on boost & ignition system, but 0.8mm.. generic gap for FI JZ

[ddeane]

From what I understand plugs are designed for a specific gap - check the caralog at the shop. If you happen to be running increased boost and want a smaller gap .7-.8mm check the catalog for the plug designed for this gap and buy that one.

Cheers Craig

[renxun]

actually why increased boost need a smaller gap? arent larger gap had more spark area to contact?

[Draven]

larger gap = more sparkto contact, but big boost is more likely to blow the spark out... so with big boost you generally have to upgrade the ignition system or reduce spark plug gap... and we know which is cheaper

[allencr]

I would never skip checking/setting the gap unless it was a real rush or I didn't give a fuck about the engine.

http://www.dansmc.com/Spark_Plugs/Sp...s_catalog.html
http://www.strappe.com/plugs.html

[renxun]

haha.... funny to say i check most of the engine condition all this while except for the plug gap only to find out that its cruicial this few days... i always thought that the gap pre-done at the spark plug factory is the most ideal .

[jeffro ra28]

Seems its pretty much been covered but bear in mind some performance plugs are designed not to be gapped. Most off shelf autoparts stock plugs however are gapable.

[renxun]

today i just open them up again for a cleaning and found out that some all of them had diference in them ... one of them had a 0.7mm, few with 0.8 and if i remembered correctly i had 2 with 0.85... so i gap them to 0.7.... just fire them up but havent bring them on the road run to see if there is any noticable difference.

in the meanwhile i found out something.. the denso iridium is quite easy to gap as the electrode is relatively "soft" ... but the HKS plugs which is also denso iridium had a very very much stiffer electrod that made me quite hard to bend the thing as well ... arent them the same thing and only repackaging been done?

[oldcorollas]

do they have "made by" on the box? were they both new, or one used?
soem are repackaged... seems unlikely for them to be able to specify different electrode material with such low volume, but you never know...

what was the original gap meant to be? it is always good to check the gap when you get them. sometimes they are not 100% correct.

[jeffro ra28]

Careful, some plugs from HKS are not designed to be gapped.