Posted By: Bigcube
What spark plug heat range? - 05/17/14 11:48 PM
I used a NGK -9 heat range for 15:1 compression. Should I change to a -8 for 11:1 and 93 octane?
Posted By: MRMOPAR622
Re: What spark plug heat range? - 05/17/14 11:58 PM
The Champion C57CX is Perfect...I'm sure if you cross that number over to the NGK you would have the Prefect Heat Range.And at 15.1 CR gap the plugs .022-.025 that will make a Big Improvement.
PS Sorry I mis-read you post that plug is for a 15-1 CR and I have never run a 11-1 CR on 93 octane before.Again Sorry for the mistake.
Posted By: ademon
Re: What spark plug heat range? - 05/18/14 03:55 AM
I use 9 NGK in my 11.25 cr, SB that has about 205 cranking psi. I run 93 don't here any knock or pinging I think I'm a little rich at idle with a 4 corner idle carb it's mostly a street car. Plugs look a little dark after 3 or 4k but what the h*ll the pistons are still in it!!
Posted By: ademon
Re: What spark plug heat range? - 05/18/14 08:04 AM
Mancini had a good NGK heat range to CR chart but I can't find it on there site maybe someone has it.
Posted By: dennismopar73
Re: What spark plug heat range? - 05/18/14 01:00 PM
Why change heat range ?
Fix issues x motor to fat. Repair carb or fuel.delivery
Getting oil contaminant in combustion chamber , fix it
Heat range is only the temp that the plug disperse to keepit firing.
Not actual cyl.temp
Not all plugs heat rang alike
NGK
http://www.ngksparkplugs.com/tech_support/spark_plugs/p2.asp?mode=nml