Is there a superceded p/n for R43CTS? This is the # called out for my 88GTA, 5.7L VIN 8. It seems the supermarkets want to sell 45 plugs, which I believe are hotter. I'm just looking for the standard plug, nothing trick, for general driving.
Thanks, FJK

 

Not that I am aware of. The R43TS is almost the same plug, the C is for Commercial, supposed to last longer if I remember right. I dont see why they would have discontinued that plug. The 45 is a hotter plug, 2 ranges.

 

I think these are the designations for AC spark plug heats, prefixes, and suffixes:

C= copper center electrode core;
R= resistor;
4= thread diameter;
5= heat range;
T= tapered seat;
S= extended nose;
X= extra-extended nose.

The copper-cored plugs were very popular for a time, then seemed to have been replaced (at least in popularity) with the platinum-tipped versions.

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The owner's manual says R43CTS. The car, as I got it, has R45TS in it with .035 gap. What to you guys recommend in a standard AC plug & what gap? I'm thinking stay with the R45TS, but with a .045 gap.
Thanks, FJK

 

R43CTS no longer exists. I have seen 2 references to the C. Copper or Commercial.

 

They probably figured this out 25 years ago. Did you get caught up in the Related Threads trap?

I like the NGK UR4 6630 V-Power Copper core/Nickel tip spark plug.

 

nope.. I'm changing spark plugs for the 1st time in 25 years Just for fun, I pulled out 1. It's an Autolite AP26. Not sure why I went with autolite 25 years ago. They don't even look too bad at all.

 

That's interesting. You forced me to look over my records just to see the last time I changed plugs. Looks like February of 2000, so right in the same period. I'm sure they were pre-millennium AC plugs, and I have no idea where I can find those any more without firing up the DeLorean and heading down the street at 88 MPH. Also, that was about 4,500 miles ago, so I think I may have some time to search a bit more for my backup supplies since I've changed my address since then.

I still maintain that the "C" designation in that time period was for copper-cored center electrodes.

 

I agree. Now they moved the "C" forward a few spaces. and I believe it's for "commercial". When 30 years ago, copper was just coming to life. Also, most listings & CHATGPT say R45TS when we know the 305 motor is R43TS. So alot of wrong information is out there.

In fact, I found R45's in my basement, that I picked up 10 years ago, and never installed. So the listings have been wrong for a while. I just brought a set of R43's to replace my AP26 autolites.

 

OK, so it's a 25 year old thread but information can get lost quite easily with how much is in the archives.

I run copper plugs in my race car but then I also don't expect them to last 100K+ miles or even anything close to 25k miles.

As for heat range, run the coldest plug possible that doesn't foul up. Check the heat signature line on the ground strap. It should be roughly half way up the strap for proper heat range. Plugs are cheap to experiment with.