Spark plug heat range

[Snake]

Ok could someone school me on a hot plug and a cold plug what do they do,if an engine is a tad rich do you use a hotter plug and so on.Would like the knowledge on this.Thankssssss.The plug I have in the 360 is the NGK GR4 2635,I have no clue on its heat rang.

 

[daredevil]

I learned a lot about reading plugs here and near the bottom they have a conversion chart and explain about the number for heat range. http://www.wallaceracing.com/plug-reading-lm.html

 

[Slappy]

Awesome info daredevil

 

[Brian Hafliger]

Ok could someone school me on a hot plug and a cold plug what do they do,if an engine is a tad rich do you use a hotter plug and so on.Would like the knowledge on this.Thankssssss.The plug I have in the 360 is the NGK GR4 2635,I have no clue on its heat rang.

The 4 in gr4 is stock heat range. so a 5 is colder, 6 is even colder...etc.
In 300-400 HP engines I like to use fr5's. From 450HP to 550 I like to use bcp6es plugs.
A 4 plug will be a bit hot if you have more than 300HP....
Brian

 

[daredevil]

Hey Brian I hear what you are saying but instead of horsepower for heat range wouldnt compression ratio be better for figuring application.Theres a lot of difference between a 400 horse 318 and a 400 horse 440. I know you are making reccomendations for a 360 but some may try and use this info on their set up.

 

[Snake]

Thanks guys.