NGK Iridium Spark Plugs

[DirtyErnie]

From what I've heard of Indexing, it may only be important if you have clearance issues between piston and plug. But, every tenth helps in drag racing.

I'm in love with the NGK Iridium plugs. Definitely felt an increase in smoothness and torque with them. I'm running the 'Kung Fu' coil and gapped fairly wide, something like. 060". I may be having some issues getting carburetors tuned because they light off any mixture with ease.
Never saw the point of running a high energy coil with a tight gap. If your high RPM is smooth, the gap isn't too big.

 

[XSLeo]

I have run the iridium plugs, I run the Autolite AP63 plugs. They both run well, no difference in starting, running or power.
The main difference I see is in the price. Locally I can get the Irridium plugs about $7 each. the AC63 plugs I used to get at Wal Mart for around $5 a pair, I just bought some online for $12.99 for a 6 pack of plugs. I bought two 6 packs. That's $2.16 for a plug that runs as well as a $7 plug.
I also run a hot coil, the Green Monster, I gap the plugs out At .038-.040.
Leo