Not a question more of an invitation to share your experiences with different spark plugs over the years. I’ve run champions in my 5.9 mangnum and nothing else until recently when I went to the Autolite 3923s. When I installed them I left them set at the stock .40, noticed a slight hiccup and loss of power, looked up if I should’ve changed the gap and someone said decrease to .35 so I did. Ran it like that for a few weeks and noticed my mpg went into the gutter it was horrible and it had this strange almost ping to it. So today, I said screw it and jumped the gap to .50 and it picked up power again, leaned out a bit and is just running better than ever! I’ll be getting a hotter accel coil soon to see more changes. What have y’all done?

 

Just plain old Cooper Champion plugs here

 

There's nothing to discuss. Use the factory Champions and don't worry about it. There's a reason it ran badly with different plugs. Stick with champs.

 

Use copper plugs of your choosing, gapped appropriately...
I use NGK.
Avoid fancy plugs (iridium, platinum, etc).

 

I would suggest using MSD spark plug wires, as they have a lower resistance to electrical flow. They do cost more, perform better, but last longer.

 

Don't bother, These have a history of crapping out. I found out the hard way when it left me stranded. I now always carry a spare. Some may like champions(copper) but i had no luck with them. Been using autolites ever since. Upgrading to 8mm wires wouldn't hurt either.

 

trying my best to get the truck leaner on fuel, getting like 5 mpg is a bit ridiculous. Seems to have perked up making the gap so large, bigger spark helps I suppose. Drop resistance, get some better ignition parts and try and get it to shape up.

 

How old are your O2 sensors? If they are recent, what brand are they? Have you fixed your plenum yet?

5 miles per gallon is a LOT ridiculous.

 

front and rear a year old bought from advance they’re the ntk brand, the plenum is all set with a gasket set from you guessed it, felpro.

 

And you still get crappy mileage????? Real curious what that is all about.....