spark plugs numbers game??
 

I am currently running NGK BP7ES, if I switch to a cooler plug like a 8 or 9 will it make any difference in how the car works? How does the number rating work? I know lower is hotter / higher is colder but what does it all mean?

Here is the chart I got the info from, search function is great too!
http://www.ngksparkplugs.com/techinfo/spark_plugs/partnumberkey.pdf

The car is a 77 with 2.7 CIS, temps lately have been getting 230ish, front cooler is not working (I know that is a PART of the problem) Also I have not had a chance to get my gas mixture tested.

I am more curious to know how the spark #'s work. I know this won't fix all my heat troubles. Just learning. :D

Shawn

Shawn,
Changing your spark plugs to a cooler heat range will *not* cure, or even affect, overall engine operating temps. All that is likely to happen, is you will foul plugs more readily in slow traffic.

On the other hand, if your engine is experiencing pre-ignition, this might be due to a plug that is too hot. A cooler one in the range is therefore indicated. (Remember....Bosch number ratings are opposite to NGK's.)

This business of spark plug heat range is all about how much heat the plug dissipates. That is mainly a factor of how much ceramic material there is in the insulator, and how much it protrudes into the combustion chamber. Most of the spark plug maker's websites go into this in more detail, if you need further info.

Keep kool, and see you at the Round-Up!

Thanks Doug. I didn't think it would help anything, but I was curious to what it all meant.

Thanks again, and yes I'll be there :D

Shawn