AC Delco R43 Spark Plugs

[Salvatore]

Yep, Autolites are good!

[47Hammer]

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]

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

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

[Salvatore]

[ 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]

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

[70 Forest Green Zee]

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]

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.

[Chevy454]

Problem is, Delco doesn't make their plugs any more...simply repackages them...wanna say they're made by the same place that makes Champion plugs? The side cut Autolites work ok. When we messed with plugs on the dyno, my beloved AC's were horrible...no matter of the heat range, they all SUCKED...stuck in an NGK, and I've never looked back...

Here's some plug info I posted a while back:

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<u>Z28 &amp; LT-1 with 186 heads:</u> my AC book calls for a C43 or an R43 plug, and the NGK site says-

Standard, V-power (3/8" reach, 13/16" hex, projected tip, gasketed seat):
XR4 / 5858
XR5 / 3332

Race, V-power (3/8" reach, 5/8" hex, projected tip, gasketed seat):
R5670-6 / 4449
R5670-7 / 5034
R5670-8 / 5657
R5670-9 / 6468
R5670-10 / 6702

<u>L78 &amp; L72 with 840 heads:</u> my AC book calls for a R44 or a 44N plug, and the NGK site says-

Standard, V-power (3/4" reach, 13/16" hex, projected tip, gasketed seat):
GR4 / 2635
GR5 / 2851

FR4 / 5155 (same as GR plugs, except for 5/8" hex)
FR5 / 7373 (same as GR plugs, except for 5/8" hex)

Race, V-power (3/4" reach, 5/8" hex, projected tip, gasketed seat):
R5672A-8 / 7173
R5672A-9 / 7405
R5672A-10 / 7942

R5671A-7 / 4091 (same as 5672, but with non-projected tip)
R5671A-8 / 4554 (same as 5672, but with non-projected tip)
R5671A-9 / 5238 (same as 5672, but with non-projected tip)
R5671A-10 / 5820 (same as 5672, but with non-projected tip)
R5671A-11 / 6596 (same as 5672, but with non-projected tip)

<u>L78 &amp; LS6 with 291 heads:</u> my AC book calls for a R43T, and the NGK site says-

Standard, V-power (.460" reach, 5/8" hex, projected tip, tapered seat):

UR4 / 6630
UR5 / 2771
UR6 / 7773
YR5 / 7052 (same as UR plug except w/ non-projected tip)

Race, V-power (.460" reach, 5/8" hex, projected tip, tapered seat):

R5674-6 / 4449
R5674-7 / 5034
R5674-8 / 5657
R5674-9 / 6468
R5674-10 / 6702

R5673-6 / 2405 (same as 5674, except w/ non-projected tip)
R5673-7 / 2817 (same as 5674, except w/ non-projected tip)
R5673-8 / 3249 (same as 5674, except w/ non-projected tip)
R5673-9 / 3442 (same as 5674, except w/ non-projected tip)
R5673-10 / 4050 (same as 5674, except w/ non-projected tip)

[47Hammer]

I appreciate the information on the plugs, I wasn't 100% sure they what they were for. I'm not going to use them myself because I'm happy with the Autolites. I may just list them on Ebay but if anyone can use them, pm me.