Thread size for a Model A spark plug

[abachman3]

My tap,that I have successfully used, from NAPA is NAPA part #T-370. Spark Plug Tap 7/8" - 18 NS.

 

[stevemclark]

Find someone else to fix it,someone you know who owns their own shop and can weld,wire welder would be best here. Take the head off,it's easy.Weld up the threads re drill a new hole carefully re tap it,retired machinist of 32 years .Guess what I do now12 years later ? What ever I want ,mostly work on old cars but when I want to and not over 14 to 20 hours a day and not over 8 days a week.I love it ,time to put the new radiator on now.Here is where you can find a 7/8 x 18 tap and the adapters. Look for SHOP NOW then scroll down to "spark plugs and parts" . https://www.mikes-afordable.com/product/T12407.html.

 

[emf]

I just checked my spark plug tap and it is labeled 7/8 x 18 SAE.



Frank