AC Delco R43 Spark Plugs

47Hammer · #1 10-12-2008, 12:13 AM

I found a set of never used AC Delco R43 Spark plugs with a date of 1995 on the box, are these considered "nos" and weren't they used primarily for 302 small blocks in '69? Do they work better than the Autolite plugs I'm currently using or are they just correct for that motor?

Thanks!

**Salvatore** · #2 10-12-2008, 04:52 PM

A little on the cold side for a street 302. I like the R44S or R45S AC's. I ran the Autolite 86's I believe and they worked good.

**olredalert** · #3 10-12-2008, 05:34 PM

------JMHO,,,,But Autolites will stay clean longer and generally run better than the same plug in an AC box. I used them exclusively in Red Alert for 8 years........Bill S

**Salvatore** · #4 10-12-2008, 08:25 PM

Yep, Autolites are good!

47Hammer · #5 10-12-2008, 08:32 PM

I have always used the Autolites,

what I'm trying to find out is do the R43 plugs have a specific application or is it a preference thing.

Thanks guys.

**Mr. Chevy** · #6 10-12-2008, 09:51 PM

I would stay away from the newer ac delco plugs they are junk

just my .02.......... Rich

**Salvatore** · #7 10-12-2008, 11:23 PM

[ QUOTE ]
I have always used the Autolites,

what I'm trying to find out is do the R43 plugs have a specific application or is it a preference thing.

Thanks guys.

[/ QUOTE ]They are a colder plug used in the 69Z's and the L78 motors. I don't know of any other application they are used for. Maybe some earlier solid lifter motor corvettes.

I don't know if the 1970 High Perf. motors used them or not. Maybe a Yenko Deuce guy will chime in. I would say more of a racing plug.

Chevy454 · #8 10-13-2008, 12:42 AM

I'll try and grab my AC plug book & see what all they fit...

**70 Forest Green Zee** · #9 10-13-2008, 04:21 AM

R43's were the standard plug installed at the factory for all 69 Z28's. In 1970 they went to the R44 for the 350 LT1 Z28's. Here in the Chi Town burbs everyone I know seems to prefere the NGK XR5 over anything..I have them in my 70 Z and my very good friend also runs them in his 69 Z. I believe that Darren (Darren X33) also runs them in his 69 Z.

**70 Forest Green Zee** · #10 10-13-2008, 04:57 AM

I also agree with Rich (Mr Chevy) that the newer AC R43 plugs like the ones you have Bart, aren't very good. If you want to run the correct plug that your car is supposed to have, then look for a set of vintage AC R43's like these with the 4 green rings....they are much better than the ones you have.