Packard Forum Index » Pre-War (1899-1942)

Need a modern day plug for my 1928 533. Can I use a Motorcraft TT10 plug? Someone suggested I use a Champion 518 or W18, but the tread depth is 1/16" longer. The current plug is a AC46.

G'day updraft,
Like to say to PackardInfo but sorry I can't help with your request.

However, I invite you to include your '28 533 Sedan in the Packard Owner's Registry here on PackardInfo.

For current spark plug recommendations I always go first to the Autolite look-up. It covers most makes back to 1920 and even earlier for some (back to 1896). If you then want to go to another make, there is a cross-reference chart provided. Autolite's current recommendation for your vehicle is their #3076.

autolitecatalog.com/PartDetailWindow.aspx?b=A&pn=3076

What a great web site for all of us who did no know about it, thanks Owen for posting.
I was going to suggest to Updraft that he use modern 14mm spark plugs with 7/8" adapters as I have in my Packards but if the correct ones are available then thats the way to go.
Also using thread adapters could affect the heat transfer from the plug and therefore the heat range.

14mm adapters??? For what??? Updraft indicates a AC 46 is currently used in the car. The 4 indicates 14mm and the 6 is a somewhat hot AC plug.

IF the AC46 have ran with staisfaction then i would certainly continue on with them. At least he will KNOW what he has when done.

If the current plug is an AC46 without an adapter, the car does not have the original cylinder head. From 1924 thru 1931 Packard used both 7/8 and 18mm plugs depending on model; 14mm spark plugs didn't come to Packard until 1931/1932.

Sorry if I confused the issue, There are adapters available that screw into the standard 7/8" spark plug hole that allow the use of modern plugs. I have them on my 126 & 633.
vintagecarparts.co.uk/products/452-sparking-plug-adaptor

DavidM, I'm just curious why you'd use an adapter since correct modern plugs are so readily available? Or are Autolite plugs not available to you? I don't know that there would be any performance difference between using the original 7/8 plug and a 14mm, it's just that when the correct parts are available, it's always been my inclination to use them rather than making some sort of conversion to adapt something else.

Good question OD, I bought them at a local swap meet many years ago before we had the internet and I while I suspected that the correct plugs were probably available in US I assumed they would be very expensive and I was, at the time buying for 3 project cars (now all finished), 2 x 8 and 1 x 6, a total of 22 plugs. The adapters were inexpensive and I could then purchase the modern plugs easily and cheaply including future replacements. I obtained advice from the spark plug agent about the best plug at the time.
Today I would buy the correct plugs off the internet

Here is an AC Delco web site probably on a par with the AL website.

parts-catalog.acdelco.com/catalog/stock_check.php

Keep us posted on what direction u decide to go. Besides, things are getting a bit slow around here now and i need something new to argue about. Gufwah ha ha ha ha.

Seriuosly tho, I am not well versed on what auto parts are readily available in Oz and what is not. So keeping us posted mite help everyone see things in a different lite, especialy me.