What plugs are You Running in Your 408 Strokers.

[MOPAROFFICIAL]

I have been running -7’s in my 340 for a few years. After pulling the plugs a few times in my now 340/420, I decided to order the -5’s after seeing a lot of buildup on my plugs. I used to run the -5’s when I ran iron heads, but was told to run the -7’s when I switched to aluminum. They should be here next week so I will throw in the -5’s and see if they clean up a bit.

Exactly.

 

[cpearce]

I have been running -7’s in my 340 for a few years. After pulling the plugs a few times in my now 340/420, I decided to order the -5’s after seeing a lot of buildup on my plugs. I used to run the -5’s when I ran iron heads, but was told to run the -7’s when I switched to aluminum. They should be here next week so I will throw in the -5’s and see if they clean up a bit.

How did it like the 5's?

 

[Squishy]

These plugs come out of my .030 over 360 with SM aluminum heads fresh from the dyno. 10.5:1 CR, 224/230 cam. Dyno operator said the plugs were perfect for this engine combo, ended up making 430 hp, 37 deg of timing.

 

[TimS]

5s run good in mine.