Service book recommends 7/8" No 18 Spark plug, what else can I use?

[Rata Road]

My 27 Chrysler 50 recommends the above spark plug. The car currently has Campion C-4's in it. Are these a correct match?

Can anybody provide a link to a cross reference guide pleas.

[dodge28]

As far as I can remember C-4 Champion was very popular interchange I stand corrected.

[Terry Bond]

I've got three references in my spark plug literature collection-

First is a small brochure printed in 1937 for Chrysler vehicles.  See photo 1.

Second is a 1942 Champion publication "Champion Spark Plug Service."  the Chrysler section s photo 2.

third item is a publication that Champion printed in 1950 listing spark plug applications for "antique cars."  Photo 3 shows the Chrysler info.

The 1942 publication includes information on substitutes and that lists the C-4 as a substitute for the 2 identified as a recommendation in the 1937 publication. It looks like the C-4 would work in your car.  It certainly would be the easiest to find.  NOS examples are easily found.

Hope this helps.

Terry

 

Edited April 24, 2023 by Terry Bond (see edit history)

[1937-44]

 A modern replacement for the Champion c-4 is Champion W-18 and slightly colder is the Champion W-16.

[Minibago]

Brass reducer from the old 7/8 to a more modern plug 14mm might be a cheaper option.

If your engine has a requirement for long reach plugs as in the earlier DB cars then a W89D is what I use.

 

 

[Frank DuVal]

I see the W89D is a 7/8" plug. Are they gasketless, or just off for the picture? 

[31 LaSalle]

On 4/24/2023 at 1:59 AM, Rata Road said:

My 27 Chrysler 50 recommends the above spark plug. The car currently has Campion C-4's in it. Are these a correct match?

Can anybody provide a link to a cross reference guide pleas.

My Chrysler 1928 conv coupe model 72 had champion c4 plugs i have changed them for c5 have been told they should be ok 

not had chance to try them yet

[Terry Bond]

2 hours ago, Frank DuVal said:

I see the W89D is a 7/8" plug. Are they gasketless, or just off for the picture? 

7/8" plugs require a gasket. The 1/2" tapered thread (model T style) don't need a gasket to help seal them.

Terry

[viv w]

I ran my series 52 for years with Champion W20 plugs with no problems, I have found out more recently that a W16 is probably better suited. 

 The C4 is used on Model A Fords and as the Model A and Chrysler motors are very similar in size and compression ratios they probably will work okay.

 Both my series 62 and G70 motors had C5 plugs that were fitted in the 50's.

[Hans1]

a little history from my books

 

Early AC Plug Chart

Chrysler 1927     Mod  50 

                      ( AC regular plug  "Y"      AC long life " L-9" )

               Regular line AC plug   "Y"         Universal line   AC  plug  " AA"        Champion  2-S ///////////////////////////////

 

Later AC chart

                   AC plug  "A"                            Splitdorf   plug  6"

 

/////////////////////////////////

Chrysler six    "50"  thru  1929

                   AC  "76"                                    Titan  "1"

///////////////////////////////

Chrysler  1924  - 1929

        Old type   C-4                                      New type      C-16C

///////////////////////////////

////////////////////////////

 

Champion C-4   to AC-76-S     Champ. C-16C   +

[Rata Road]

Thanks Guys, lots of great info.

[dodge28]

More than you can throw a stick at. At least, members are listening and responding, Great fellows, thank you all.