Ok the concept of using spark plugs for different applications musta just flew over my head for a while now.

So I'm racking my brain learning about heat ranges and such. I still don't quite understand how to find it when searching for plugs but I think part of it deals with plug reach and the material used?

I'd like to get some Rapidfire plugs. Except I don't know what to go with. I have a 355, vortec heads, ~10:1 compression. I'd like to run nitrous sometime. So I think I should go with a slightly colder than stock plug. Do I go with Rapidfire #12?

"Spark Plug, AC Delco, Tapered Seat, 14mm Thread, .625 in. Reach, Resistor, Each"

I read in another thread (yes i've been using the search function extensively) that someone was having good luck with the NGK TR55, which is not platinum and has a .708 reach. It was replied to, that for stock application that is pretty good but too hot for running any boost or juice. So would that mean running platinum tip with .625 reach is good choice for a colder plug to run? The rapidfire 12 is listed as the performance replacement for vortec engines (I used a C2500 5.7L from 1996 for reference)

 

My setup is similar and i just run AC delco stock replacement platinum. So far neither engine has had a problem running these but if you are looking for every little bit of power all i can say is play around with them since no engine is completely the same.

 

The odd thing about that is the stock replacement is nearly 6 dollars per plug and the rapidfires are a little under 5 dollars. Any info on the stock replacement?

 

I don't think there would be anything wrong with the rapid fire's .. in fact i think i had rapid fires in there one time... and the autolites too.. really no difference to me and i think right now its just the 41-932 that i have now.. just make sure its the correct plug reach.. the old style plugs like for 70's cars will go right in but the reach is like .2 smaller.. then in that case yea you would notice a lack of performance..i did

 

https://www.thirdgen.org/forums/tech...ark-plugs.html

The only difference is that the vortecs take the longer reach plug. Do a search on F-bird'88, I know he's spec'ed some out before.

10:1 will make you want to jump down 2 heat ranges from stock or so. Drive it around for a while and read the plugs after some full throttle high RPM blasts. Look for the heat line on the ground strap. Then swap plugs from there.
Skip the platinum, they're only good for cars that are REALLY hard to get to the spark plugs, so you only want to change them every 5 years or so. Get copper ones, much cheaper, and they work better. You just have to change them more often (since you'll be reading your plugs, that's fine).