Topic: Indexing Spark Plugs

I daily a Gen 1 Insight, which uses indexed spark plugs from the factory. The engineers who built it were so crazy the head is stamped with the proper type of plug to use. … plugs.html

Do I really need to buy the $10-12 plugs indexed plugs specific to my engine?

People on Insight Central indicate that indexing is critical to achieving the 23:1 air-fuel ratio in the fabled 'lean burn.' Spark plug indexing washers are an option, but by the time I buy decent plugs, the cost will be the same and I am 100% certain I will lose the indexing washers before I need them again.

Re: Indexing Spark Plugs

Isn't this Lemons? - here's your $0-and-worth-every-penny advice from one cheapskate to another:

- go buy your non-indexed iridium plugs, saving $6 each (and there are only 3 on the 1st gen Insight, as this ain't no fancy 4-cylinder ride)
- drink a beer.
- save the can for shim stock
- go to your buddies house to find a hole punch the right size
- talk for two hours over his Lemons car, make plans to work on it, drink another beer, etc.
- come home, install plugs and shims, find that you've forgotten what your index marks on the plugs mean, say 'f' it.
- and now you've spent a whole day changing 3 spark plugs and are OK with it

. . . but, more seriously, had you miked out the plug gaps?  Mine had worn just to Honda's max spec from new to 100k miles - if yours are newer than that they may not even need to be replaced.

(btw., check valve lash if you're in there)


Re: Indexing Spark Plugs

Wow.  Did not realize that there were any factory indexed plugs.  I doubt you will notice any difference if you index the plugs.  The likely reason for this is emissions related.  They probably squeezed out a 0.01% decrease in emissions by indexing the plugs, so it was worth it to them.