Spark plug differences question

[VAL]

So I went to put new spark plugs on my truck today. My truck is an 86, but its got a newer 92 carbureted TBI head engine. I got home started pulling the plugs and to my surprise, the new ones were shorter.
Here's some pics.

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I installed them anyways, and my truck runs so much better & smoother than ever, even better than when I had the engine rebuilt a few years ago. Seems to have a bit more pep than before.
I was just wondering why I had the longer plugs in there. Maybe they are for an 81-86 350CI?

 

[350runner]

What plugs are the new ones?.

 

[VAL]

What plugs are the new ones?.

Bosch platinum plugs for a 92 350CI

 

[MadOgre]

Those new plugs sit in exactly the same place inside the combustion chamber. They are only shorter on the outside. The bosch plugs are simply a superior plug compared to your old ones.

 

[chengny]

2 X what MO says.

The distance from the shoulder (at the top of the threads) to the bottom of the insulator leg is a good indication of a plug's heat range. That is really the only fundamental variable in any spark plug.