different of hot and cold plugs
 

I've been trying to find out the different in hot and cold plugs. I mean physically, which one is shorter or longer,how can you tell because I've been buying the wrong type of plugs for the nitrous

A 'colder' plug should be shorter than a 'hotter' one.

For example, I use Autolite #3924's in my Mustang. For you, with nitrous, you'll probably want to use a #3923 - or a colder plug.

Hope this helps.
E