LaSalle spark plugs

[jpm123]

What are the correct spark plugs to use in my 1927 LaSalle (303 cu. in.)?  And where is the best place to get them?

[Warren Rauch]

  The factory plug for1927-28 was an AC type"A". This was a standard plug with 7/8 x 18 threads. In those days  they didn't have heat ranges so if it bolted in it was right. The best match for it today is whatever they are selling for Model A Fords. (AC type 78s or Champion C16C)  Don't get 18mm plugs they look almost the same, but you'll need 1930 heads to make them work.
   Try farm supplies or Repro Ford parts dealers.  Warren

[Otto Skorzeny]

 What kind of plugs are in your car now?

Champion must have changed it's numbering system. The cross reference for C16C is now W16Y for the 7/8" x 18 plug you're looking for. You should be able to get them anywhere or order them directly from this site:

Here are the relevant stats:

7/8"-18 TPI Thread
16mm (5/8") Reach
15/16" (23.8mm) Hex Size
Heat Range 6
Standard Coil .025"
(0.635mm) Gap

http://www.championsparkplugs.com/results_cross.asp?pid=c16c&x=45&y=12&seenCrossWarning=1

[jpm123]

  The factory plug for1927-28 was an AC type"A". This was a standard plug with 7/8 x 18 threads. In those days  they didn't have heat ranges so if it bolted in it was right. The best match for it today is whatever they are selling for Model A Fords. (AC type 78s or Champion C16C)  Don't get 18mm plugs they look almost the same, but you'll need 1930 heads to make them work.
   Try farm supplies or Repro Ford parts dealers.  Warren

Thank you for the info.  John