Hi Guys, looking for plugs, the manual calls for AC R42CTS the parts store has R42TS so whats the C mean, I am thinking good old AC plugs is all I need, if you have any other in mind please let me know.

The car will not be driven much so stock plugs should be fine.. ( I think ) With that said the car has the factory plugs with 13K on them, should I even bother to replace them ?

PS planing on new cap and rotor and wires too ? should I based on age ?

[This message has been edited by hunter29 (edited 03-18-2020).]

The C may stand for 'Commercial' according to internet guessers. At any rate, what you want is the R42TS copper plugs if you want to change them, but they should be good for a lot more than 13K miles.

[This message has been edited by Gall757 (edited 03-18-2020).]

The Fiero seems to like the recommended factory plugs best. Champion or AC. Lots of owners have reported poor performance out of the fancy plugs. Gap at .045-.047. Some have said they went as far as .050 for a hotter spark but beyond that they started having misfires and weaker spark.

GM HEI and DIS engines Can use better plugs but can hate other "better" ones like Many Gimmick plugs that cost more and do nothing if your lucky. DIS Hates BOSCH +2 and +4 and others. Some may remember Split Fire and others got sued by FTC and more for false ads and even wrecking engines.

Main thing for Fiero is use better plugs w/ nickle etc coated metal shells that are way more rust preventive then most standard copper plugs. You find water just from washing can rust Fiero plugs easy.

HEI can use any basic Platinum plugs from ACDelco and some others. Fiero V6 ACDelco 1 Rapidfire (Yes 1 is the PN)

DIS can use "Double Platinum" plugs from ACDelco or Autolite. These put Platinum on tip and ground arm so ones that fire backward sees exact same setup. Example: 87-88 L4 can use AUTOLITE APP666 or ACDelco 41-816 Double Platinum Spark Plugs.

Note: RA and some others has NOS of older plugs or simple have wrong data. I get plugs locally and check I get right part before leaving store.

When removing plugs for any reason use compressed air and a wire to stir up and blow out crap before you use a wrench.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

I always use ACDelco No 41809 for its resistance to rust "the shell is made of stainless" Remember how difficult it is to remove the 3 spark plugs from the firewall side when they are rusty!

More Information from Rock auto for ACDELCO 41809 :

* Dual platinum tip for improved resistance to spark erosion, fouling, and corrosive combustion chamber environment

* A platinum center electrode and a platinum pad lower the ignition demand voltage

* One-piece integral suppressor seal helps reduce radio frequency interference, meters spark plug energy to help provide long electrode life, and seals against compression leakage

* Designed with corrosion-resistant shell

* Spark gap remains virtually unchanged during the life of the plug

[This message has been edited by claude dalpe (edited 03-19-2020).]

Thanks. This is good info to know, especially about the anti-corrosion plating. We all know how stubborn Fiero spark plugs can be.

Thanks for the info...

quote Originally posted by sledcaddie: We all know how stubborn Fiero spark plugs can be.

Worse when many way over torque Spark plugs (and oil filters) when installed. Even easier when also use "anti-seize" on them.

Plug's Cone is locking and sealing for the plugs and that hates anything on the cone shape.
Might use a little anti-seize on threads but throw away any torque data because Nearly all torque tables are only for clean dry threads.