what is the best brand of sparkplug to run in a stock 400 motor? thanks

 

AC Delco

Gene

 

it wasn't mean't to be a loaded question. i have had good luck with champion plugs. what would be the correct part number for them. i am asking because i put new autolites in it and hasn't run right since. and want to make sure i get the right ones. thanks

 

I didn't think it was. You ask what was the best and I gave an answer, thats all.
In your book it gives you the AC number, just have your parts guy cross reference.
Gene