Originally Posted by b_kennedy
Anyone know where I can purchase washers or flat nuts that will fit a spark plug thread. Think it is 13mm. I have tried a m12 and m14 toothed washer and they are no good.
The washers with teeth are called "shakeproofs", the ones with external teeth are known as "external shakeproofs".
The nuts with teeth are "serated flange nuts".
Any good fasteners/fixings shop should have them in stock.
