Heat Range Help

[JP53-N]

I dug up a bunch of spark plugs and was wondering if someone can help me with heat ranges. With reach aside, can someone let me know from cold to hot what order these plugs would be in, in relation to a J2J and a J4J Champion?

Autolite Racing A23
Champion J-57R
Champion L-2G
AC M42K

Any help would be appreciated. I'd like to be running these in engines but need to do this homework first.

[ricochet112]

Champion plugs go hotter with higher numbers.

[Carbon Core]

Sparkplugs.com is a very helpful web site. all you have to do is punch in the plug numbers and you can compair heat ranges.

[JP53-N]

Thanks for your input. Cool website reference, but most of these plugs aren't listed there. Does anyone know what racing engines the J57R's or Autolite A23's were used in? They both have a recessed gap design with the ground electrode being a cylindrical bar coming in from a hole in the side of the recess where the center electrode is down in.

[ZUL8TR]

heat ranges

I dug up a bunch of spark plugs and was wondering if someone can help me with heat ranges. With reach aside, can someone let me know from cold to hot what order these plugs would be in, in relation to a J2J and a J4J Champion?

Autolite Racing A23
Champion J-57R
Champion L-2G
AC M42K

Any help would be appreciated. I'd like to be running these in engines but need to do this homework first.

This info from the "Champion High Performance and Racing Heat range Chart and Tuning Quide" I received from them in the 1970's. Note that the heat range comparisons in this Guide are approximate relative comparisons and they advise that testing and accurate plug reading are essential to select the correct heat range for a givin application. Additionally heat range cross referencing of different brands are generally not direct equivelants.

BTW this is a great Guide with lots of tech info but NLA.

Here are their relative comparisons.

Champ recessed series 3/8" reach 14mm hot to cold: J62R, J60R, J57R, J54R
The J2J about same heat range as J60R and the J4J is hotter than the J62R.
Note that the gap styles are different
The Autolitre A23 is about same heat range as the J62R
The AC M42K is about same heat range as the J4J

Champ L series 0.472" reach 14mm hot to cold: L4G, L3G, L2G, L55G
The J2J is between the L4G and L3G and the J4J is hotter than the L4G
The Guide has no L series equivelent listings for the Autolite and AC plug numbers you posted.

[JP53-N]

That was exactly what I was looking for. Thank you for taking the time to look it up. Now I know where to start.