Re: Help 1978 mercury 1150
The trigger on that motor is non-removable from the distributor housing. You can buy a remanufactured trigger (and housing) from CDI Electonics and other places on the web. Those triggers were very common on the Merc inline 4 and 6 cylinders from the early 70s thru early 1979. I do not know about the one you mention, since you have not identified it sufficiently. If it uses the same switchbox, it is probably the same. Make sure it has the six-window ignition disk, like you original has.