I am thinking about going to the NGK'S but they do not have BR7EF only BR7ET. What is the difference and will they work? I currently have the IT20's but they are not cheap.

My mods, 4#, chip, filter.

 

Not sure what the difference is on your question but, for only a #4 pulley a BR7 is way too cold of a plug. I run the TR-6's with my #4. I tried a set of BR7's a while back because I didn't know any better and the truck barely idled.

 

That's quite interesting,I guess i may have to goback to my IT20's then. I will keep that in mind. I was going off a plug chart I saw in another thread, and it says that the 7's could be used from 4# upward

 

Outside looking in here ::: I ran the BR7EF in my Gen I with no ill effects .. I ran lean thats why I ran them. If you look at the BR7EF and the TR-6 NGK the center electrode on the colder plug is recessed more up in to the jacket of the plug. These are better suitted for NOS runs. Not having the ground electrode pertrude into the cylinder is better for NOS spray. There is a less chance to { Create hot spots }....

 

I don't run a pulley any more, however I run the TR-6s cause they work and are cheap.