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Hello
Wath spark pluge do i need in a 327 engine from 1953 packard .
I have autolight 308 in now . But i am Not shure if its the Wright one

Autolite 308 is a correct choice. When in doubt about current spark plugs recommendations for Autolite, you can use this site:

autolitecatalog.com/Application.aspx?b=A

Interesting site. Four plugs are listed for my 456: double platinum, platinum, resistor and non resistor.

Which is preferable, and why?

Pat, your questions do continue to surprise me.

Resistor plugs and resistor wiring are methods used to suppress interference with the radio from the high tension ignition. Normally you want one or the other, not both. If the radio reception is unimportant, I'd go for neither and get the benefit of a hotter spark. If radio reception is important, my preference would be for non-resistor wiring (it lasts longer) and resistor plugs. You might even get away with neither as some of those distributor rotors had a resistor in them.

As far at Pt or double Pt, in my opinion you're just throwing your $ away on them.

Delco distributors may have a resistor rotor, which is problematic. Better to use a non-resistor rotor and wires, and as O_D suggests, resistor plugs.

Auto Lite distributors use a spring loaded carbon plug in the cap. This may be enough for TV and radio suppression with non-resistor wires and plugs. If not use resistor plugs with non-resistor wires.

(o{}o)

Very appropriate topic for me right now. Similar situation, 327 engine, (54th Series), what plug to use?

THE SPECS SAY:

Champion J8, 14MM .023-.028 gap

OK, not much selection there, so 26th series, 1953:

Champion J8 etc. etc. (same gap)
Autolite A5 same gap
AC-46-5 same gap

These are listed across the board for all engine sizes for 26th Series.

WHAT I FOUND IN NAPA WORLD:

The only crossover found (for what it's worth) is an AC-R45.

Guess what plugs were in it when I got it? AC-R45. (Also a full set of used "spares in the trunk" AC-R45.)

So that's what I bought.

The problem sort of solves itself based on what's fairly close to the right part and is available over the counter.

Anything anyone could add would be much appreciated. I especially would like to know if those metal rings on the plug base should be left on or thrown away. Are they worth anything?

AC-R45s are going to be a step cooler than the specified AC-46. The "R" indicates it is a resistor plug. The "45" is the reach and heat range. They may work, but are a colder plug than specified. The resistor feature should not affect performance unless you have resistor wires and/or a resistor rotor. If so, go to a non-resistor rotor and wires when using the resistor spark plugs.

(o{}o)

Thanks for the info on heat range. I suspected the "45"s might be a bit "cooler" but could not find an AC "46" heat range.

Could the gap --either larger or smaller-- help the colder plug to perform better? I imagine they'll foul quicker than a "hotter" plug, probably the reason that the former owner had two sets-- one to run with and one to clean.

For my purposes, they'll probably be OK, and they weren't expensive... about 2 bucks apiece.

I haven't installed them yet, and might hold out for a more o.e. type plug if I can find a set. I've had good luck with Auto-Lite in other vehicles, and if the 308 is available, they may be worth trying first.

Even though Champion was specced, I guess everybody knows Champion's current reputation-- bad. I don't even know if I could get a Champion J8 or crossover number, nor would I probably want one.

I think I've got Auto-Lite ignition so the Auto-Lite would be more "correct" in a way than AC Delco, although being correct is not my main goal--drivability and starting are.

That said, with the R45 AC plugs in there now--although cruddy and probably not gapped very well--the darn thing starts like it has electronic ignition.

I hope this discussion helps the original poster. Even something as simple as a spark plug has a learning curve in this blasted hobby.

And what about those rings? Leave them or toss them?

Those "rings" are the gasket that seals the plug/head interface & keeps that compression stuff inside where it belongs.
You will notice that they crush slightly when tightened.

Although an old racer trick is to leave them off for a tiny increase in compression. (if the plugs still seal).

Use the "rings"!!!!! Even a good used one not broken is ok. The 45 heat range should be ok.

Quote from post #8 above:
"I guess everybody knows Champion's
current reputation-- bad."

Thank you. Believe it or not the baby boomer set is still living in 1965 and many refuse to accept that nor understand why even after drawing them a picture or even painting them a rembrandt.