My friend has just picked up a cheap 7.5hp Mercury(thunderbolt ignition?)
Been stood for a fair few years.
So we thought we would have a go at a service.
Carb off with a good clean and fresh pertol/oil mix.
Fitted new impellor.
Greaseed up etc.
But then it came to the spark plugs.I have never seen anything like them
They look normal except there is no arm on the bootom of it.
Bit difficult to describre really but on a standard type plug there is the little pin on the bottom with the arm over it that you gap with the feeler gauges.
These dont have that arm.The pin is there and thats it.
They do work as we have now had it running but like to replace.
Have got any pics but engine is the same as this.