Spark Plug for 78 Eldorado 425 ci 4bbl

[Jakes]

Hi All.. My '78 Eldo has the standard 425 ci 4bbl motor.  The"book" calls for the ACDelco R45NSX plug which, I believe, is no longer made.  Is the ACDelco R45XLS6 the replacement plug?  Any other plug brand recommendations....Autolite, Champion, Bosch, etc?  I read recently that, overall, the best type of plug is the standard copper core type rather than platinum or iridium, due to Cu's electrical conductivity properties.  No doubt there are opinions all over the map.  Please advise....many thanks.

[TJ Hopland]

I too wonder if there is any benefit to fancy plugs in an older motor especially one that is not a daily driver getting a lot of miles.

["Cadillac Kid" Greg Surfas 15364]

Paul,
The AC Delco R45XLS6 would be just fine.  If you want to choose an alternate plug, be sure to select the proper reach aqnd heat range, but I am a firm believer in AC Plugs.  They have NEVER let me down.
Greg Surfas

[R Schroeder]

Greg is right, but here are some others.

Replacement spark plugs for AC DELCO R45NSX:
Accel 0496
Autolite 646
Bosch WR9DCX
Champion RN16YC5
Denso IW16
Denso W14EXR-U11
Denso VW16
General Motors 5613566
NGK BPR5ES13
Torch F5RTC-13

I run NKG Platinum plugs in my 78.
I also have a set of NOS R45NSX plugs for my car too.

If you want AC, keep checking Ebay. They do come along from time to time.

Roy

[Jakes]

To Will Harrison... are the Bosch's you installed standard copper core or newer type platinum or iridium?

[R Schroeder]

Iridiums are what come in most new cars.
Tough as nails. Step above Platinum.