NGK Spark Plugs

[GTPJIM]

Can anyone tell me for sure if NGK TR5 Spark Plugs are identical in heat range to NGK TR55, as I have been informed that the only difference is gap size, is this correct?
If the heat range is identical, is it also the identical heat range to an Autolite 104 spark plug?
I am presently seeing 1.5* at WOT with my present setup with Autolite 605's installed and am considering going to a colder plug.

[Fivefingerdeathpunch]

605's should be just fine for your mods, but going 1 step colder won't hurt anything. I doubt much will change.

But TR5 and TR55 are pretty much the same, I think the TR5's come in a .040 gap already, so it's smaller.

[GTPJIM]

Thanks for your reply but are the NGK TR5 the same heat range as Autolite 104?

[231FUN]

Thanks for your reply but are the NGK TR5 the same heat range as Autolite 104?

No
An AL 104 is two full ranges colder than stock while a NGK TR5 is only one full range colder than stock.
http://www.oqcgp.com/phpbb3/viewtopic.php?f=44&t=37950

[GTPJIM]

Thanks so much for the reply and the link.