Use an Ohm meter to check the resistance through your spark plugs when you have them out for cleaning. Non-resistor plugs should be zero Ohms, most resistor plugs at 5000 Ohms. If not close to the above figures then it’s time to replace them – perhaps try a different brand!!!
You are measuring the resistance through the plug from the top to the tip of the central electrode – along the route the spark goes.
Visit …. The Green Spark Plug Company for a full selection of spark plugs and other servicing components.
MGB tips mods and maintenance 