Discussion Starter · #1 ·
I have a 91 GT with a vortech 8-10psi. what is a good spark plug and do I need to run a colder plug. If so how much colder than the stock ones.
Go with Autolite 25's (copper core). If you run 87 octane, I'd gap them at 40, if you run 91, gap them at 35.I have a 91 GT with a vortech 8-10psi. what is a good spark plug and do I need to run a colder plug. If so how much colder than the stock ones.
Fox Body Mustang's run the best with basic copper core plugs. Just because an automotive product is the newest and most expensive technology, doesn't make it the best. Everything having to do with cars is application specific and it's impossible to make a product that is the BEST choice for every car. You need to remember what the technology was like in 1991 (the 5.0L in question), ultra new, super expensive spark plugs were not designed for this particular motor. Why? Because it's been proven 10 times over that Motorcraft or Autolite copper core spark plugs are the BEST selection for these motors. Comparing the spark plug operation on a Dodge Dakota really doesn't compare to the operation of a Ford Mustang, at all. The Dakota r/t is a hell of a lot newer and is controlled more by the ECU and less from analog engine components. "Newer is not always better".I'd go with NGK Iridiums. They made a noticeable difference in gas economy AND power. Iridium plugs are the best, newest, and most expensive technology out right now. Autolite does make a version of the Iridium plug too. My friend bought those for his Dakota R/T and loves them.
Yes that's true.Platinum, Iridium, etc. are NOT pure to the core. They are just a coating over a copper core.