Spark Plug socket size for v8 head plugs

[ricky8664]

As I've been unable to find my imperial socket set which includes 3 x thin walled socket spanners, I decided to buy a set of just the socket spanners.

Got a set of three (14, 16 and 18mm) without really thinking and went out the other day to remove the one stubborn plug which had refused to come out before we started the engine.... and they're all too small!!! 

The only bigger size spark plug socket I can see is 21mm. Before I go out again and order the wrong size, could someone please confirm that a 21mm thin walled socket is the correct size for v8 head spark plugs??

[jorhenderson]

mine measure at 20.6 mm that is 13/16 unf

[lagain]

There should be a plug socket in the tool tray, under the radio.
When you refit the spark plugs always put them in by hand. It is very easy to cross thread them due to the alloy head.