383 spark plugs

[olddog67]

I am changing the plugs in my '67 Charger, I was going to replace with what was in the car as it seemed to run pretty good in the fall beside a small pinging at hard acceleration but I attributed that to old gas as the PO said he had not put more than 50 miles on the car in the last year. Anyway I pulled the old ones today and they are AC Delco R43S. I know nothing about plugs and the numbers on them so am looking for some feedback.
I did some searching and Champion RJ12YC or Autolite 85 seem to be the more common for a stock 383.
Thanks!

 

[Lionized]

I'm switching back to Champion after NGK.

 

[texas69bee]

RJ12YC or Autolite 85 will be fine. It's a good starting point to see how it burns.

 

[PurpleBeeper]

I've only every run Champion RJ12YC's.

 

[miller]

Champion RJ12YC

So you know, the R in front means it's a resistor-type, like for electronic ignition. C at the end, is for copper. It will work fine, but probably not the original plug number.
If your running a point distributor, normally you would use a Champion J12Y...since J11Ys can't be found these days. I'll add, these plugs are usually used with wire core plug wires, copper, or stainless steel.

 

[Ranger16]

Would there be a problem with using an equivalent heat range plug with platinum or Iridium tips for longevity?

 

[Lionized]

Would there be a problem with using an equivalent heat range plug with platinum or Iridium tips for longevity?

No problem. Just remember that iridium/platinum is a slower /longer spark. These plugs are designed specifically for longevity, not maximum spark ability.
For our cars copper core is the correct answer.
JMHO.

 

[Ranger16]

Thanks. Considering how many miles get put on it per year, I'll just stick with the J12Y's.

 

[RJRENTON]

OldDodge,
There are many different options and opinions as which may be best. AC R43S are good...Champion RJ-12YC are good also so are the NGK equals.
I use Champion UJ -11G or Champion HO-8A both still available but hard to find. I also bought 20 sets of Mopar P34P made by Campion and are equal to Champion J-11Y which were factory installed. Look at the Internet for plugs....
Bob Renton