They Don't Make AC-45 Plugs Anymore

[Donald M.]

Another tradition bites the dust! I am now stuck with using AC-R45 plugs. What,if any,is the difference in performance, longevity, etc.with a resistor plug vs.45? Or perhaps someone knows where I can get some 45's.

[Dave S.]

Re: They Don't Make AC-45 Plugs Anymore

Don,
Any AC plug you buy today is of the Made in Mexico variety and would be of inferior quality to the older AC spark plugs. The R style plug should perform as well as any non R plug for street use.

[John H.]

Re: They Don't Make AC-45 Plugs Anymore

I've used the current issue version of the R45S in all my small-blocks (with stock ignition, wires, coils, etc.) for the last two years, and have no complaints about them; they work fine for me.

[Roy B.]

Re: They Don't Make AC-45 Plugs Anymore

I have the original 44 plugs in my 55 Corvette for 20 years and as longe as the electroy has not worn thin I just clean them with a plug blaster you can get at any parts house once a year.You can still find them on E-Bay for your Vett. now and then.

[Dave Suesz]

I was stunned to discover...

in the 1955 AMA package I got from Chevrolet that the plug listed for the '55 was an "R". The old non resistor Champions in the engine were the ones the engine builder put in 20k miles ago (thirty years!) so as part of the next tune-up I went with the current version of the Chevy specified Delco (either R44 or R45, I forget). Car runs great! Don't worry about the "R", I think the radio got a little clearer, too.

[Roy B.]

Re: I was stunned to discover...Dave

My original plugs are 44-5 that I have always used , you can still find them out there. I also have a new original set of AC commercial 43-5 that look the same as 44-5 I have but for the bottom electro area.

[Duke W.]

Re: They Don't Make AC-45 Plugs Anymore

If you want a non-resistor plug of equivalent heat range to the AC 45 both NGK and Denso make them - B4 and W14-U respectively.

The resistor plugs became OE on Corvettes in the late sixties or early seventies and appear to work OK with the single point ignition, and they do provide more EMI suppression.

Duke