HOME and how to join Forum Open Area General Scott topics Sparkplug inserts Re: Re: Sparkplug inserts


Both the ferrules and the ring nuts are R/H thread. You shouldn’t really be tapping them as there is a risk of slipping and damaging the water dome casting, and of course it also chews up the ring nuts. It is bodgery ! Get a piece of thick walled steel tubing of about the same O/D as the ring nut, then mark the end to correspond with the castellations on the ring nut, cut down about 3/16″, and then cut and file away the tubing to leave the end with pegs that will engage with the castellations. Drill a hole through the other end of the tube to take a tommy bar, and now you can easily unscrew the ring nuts without causing any damage. When they are off you can put a screwdriver or tyre lever in the gap at the front of the dome, and gently lever up the dome to remove it and reveal the rest of the ferrules. There should be a nice flat ledge around the edges of the ferrules that the sealing washers sit on, but if these are badly corroded the ferrules will need renewal, and can usually be removed by unscrewing, using a pair of Stillson grips. As they are going to be renewed you could take an angle grinder and form a couple of flats on the sides at 180 degrees to one another, and you will then get a much better grip on them. Your ‘piston slap’ may be nothing of the kind…… Typically it will be a gudgeon pin hole that has worn oval due to the pin turning in the piston instead of in the little-end eye in the conrod. If that is the case it will be best to get both pistons bushed in order that both weigh the same afterwards.