I recently changed the spark plugs in my ST. They were the originals by their look. They looked fine (20,000Km) but swapped them anyway.
I fitted Iridium plugs and noticed the original plug removed has a 'shoulder' immediately below the seating washer. This shoulder is larger in diameter than the thread below it and fits snugly into a pocket in the head I could see.
The Iridium plug (CR7EIX) has no such shoulder and this looked like a disadvantage as the pocket in the head was not filled and the long thread of the Iridium plug hovered in 'thin air' down through the pocket space before threading in below. (I hope you can visualise what I'm describing - well done if you can!).
My question is: Is there a problem with the Iridium plug threading way below the seating washer and the pocket in the head not there to lend support to the plug?
Thank you.
I fitted Iridium plugs and noticed the original plug removed has a 'shoulder' immediately below the seating washer. This shoulder is larger in diameter than the thread below it and fits snugly into a pocket in the head I could see.
The Iridium plug (CR7EIX) has no such shoulder and this looked like a disadvantage as the pocket in the head was not filled and the long thread of the Iridium plug hovered in 'thin air' down through the pocket space before threading in below. (I hope you can visualise what I'm describing - well done if you can!).
My question is: Is there a problem with the Iridium plug threading way below the seating washer and the pocket in the head not there to lend support to the plug?
Thank you.