SPARK PLUG HEAT RANGING

I have had good success with the NGK spark plugs running my builds that use vortec heads. Here's what I have learned about finding the ideal heat range. The crate 602 likes the #8 due to it's limited compression. In a 10 to1 compression build the #9 was perfect and when I have run more than 11 to 1 compression, the #10 plug worked well. Remember, for NGK plugs ranging is higher number = cooler plug!