1966 Spark plug issue

[Mikey78]

Howdy Gang,

I bought some spark plugs for my 66 thunderbird. 390 4 barrel. The spark plugs they gave me were "correct" for the 390 engine but they were smaller than the ones in the block. The ones I bought fit a 5/8 socket(motorcraft plugs) The engine plugs fit a 13/16 socket.

I'm guessing she gave me the wrong plugs.

The plugs in the engine seem to be bigger? Am I having a brain fart? What am I missing here?

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[jack-in-sac]

Howdy Gang,

I bought some spark plugs for my 66 thunderbird. 390 4 barrel. The spark plugs they gave me were "correct" for the 390 engine but they were smaller than the ones in the block. The ones I bought fit a 5/8 socket(motorcraft plugs) The engine plugs fit a 13/16 socket.

I'm guessing she gave me the wrong plugs.

The plugs in the engine seem to be bigger? Am I having a brain fart? What am I missing here?

No you are as sane as the rest of us for what that is worth. You want the plugs that are 13/16". You were not given the correct plugs. You may have been given plugs for a 390 just not a 1966 390. Take them back and exchange them for the correct plugs.
Good luck J.
It has been my experience that for my old cars I have to know what I want because the person behind the counter has trouble with any part for a car from before they were born.

 

[Mikey78]

That's what I thought. I went back and said I believe you gave me the wrong plugs. She checked the computer to my amazement she found the "other" plugs. Thanks for the reply.