1960 Spark Plug Difference

[Tom Hitchcock]

Can anyone tell me the difference between AC plugs "R44S" and "R45S" and, should I use the R45S in my 1960 Coupe de Ville?

Thanks guys!

Tom Hitchcock
CLC - 2212

[Misfit]

The 45's are one heat range hotter. The hotter the plug, the better it will completely burn the mixture delivered to it.
If you do nothing but open highway driving, then the cooler plug will suffice. (44's) Either way you won't notice any difference in the running of the car.
When you pull the old ones out and they are a nice tan color, then your engine is happy with what it has in it for the application being used.

But when you check the stores, you won't find 45's anymore. Only R-44S and R-46S are available. I have the best results with the 46's as I do a combination of city and Interstate driving.

MisFit

[Tom Hitchcock]

Misfit,

Thanks for your concise explanation. You didn't say so, but would you speculate the reason behind phasing out the "44s" and "45s" was prompted by today's fuels? 

I want the gas to burn, not explode, in the combustion chamber and am somewhat "gun shy" about putting in plugs that are too "hot" for the 390.  Most of my driving is in rural, non city, settings with an occasional trip on the Interstates.  Not much stop-and-go stuff and i no longer participate in parades.

I discovered I have a set of new R45S plugs, so in view of the above, do you feel they would still be okay.  You know, I gotta take care of the old girl!

Tom

[The Tassie Devil(le)]

G'day Tom,

The difference between a Hot Plug and a Cold Plug isn't in the temperature of the actual spark, but the length of the Porcelain that the Electrode is covered by.

A Hot Plug is designed for running in an engine that might be suffering from burning oil, and it takes longer for the carbon build-up to stay in place around the Electrode.  This "Heat" is designed to assist in burning away the contamination and keeping the plug operating longer.

The Cold Plug simply had more Porcelain around the Electrode, which allows the centre of the Plug to run cooler, but in an oil consuming engine, this allows the Electrode to foul up sooner.

Take a gander inside the Spark Plugs, and wou will notice the varying lengths of porcelain and you will understand what I am talking about.

Bruce.

[Misfit]

Tom, I've had the 46's in my '59 with a '61 drivetrain for 4 years now. They burn exactly as they should. All I've done is increase the gap to .045 since the installation of a Pertronix Electronic Ignition System, with the 45,000 coil. Or is it 40,000 volts. I don't remenber.
And they have been there for almost 25,000 miles, with no problems.

Maybe I should take a peek at them. Nah....it runs fine. Leave well enough alone.

MisFit

[David King (kz78hy)]

Misfit,

Thanks for your concise explanation. You didn't say so, but would you speculate the reason behind phasing out the "44s" and "45s" was prompted by today's fuels? 

Tom

I think the reason the 44 and 45 plugs were phased out is all the newer cars started using resistor plugs (that is what the R stands for) to lessen radio interference.  I bought a set of NOS 44 AC Delco fire ring plugs on ebay for my Brougham.  My car has all the condensers/capacitors and I get no radio interference, AM only of course, and I have a 55 amp generator spinning away.

David

[Tom Hitchcock]

My Thanks to Everyone for their words of wisdom and encouragement. 

Speaking for myself, thanks to those who responded, my knowledge of yet anther segment of our hobby is a bit less foggy. 

[Walter Youshock]

I just got a set of AC R45's (NO "S") at AutoZone for my '57.

If these have now become that hard to get, I'm going down and buy out their entire stock.

The last straight 44's I got was back in 1997 at a local supplier.