55hp Evinrude "Blew up" Need some advice.

I have a 14" Doral fibreglass boat with a 1968 55hp Evinrude.
I went boating and boat was running for 5 minutes and shut off after many tries I finally got it started as I started speeding away the motor started chuging then I heard a very loud
'BANG!!" when I looked back the motor cap blew of and was on fire I put the fire out on the cap and when I went to look at the motor everything looked fine except for one of the spark plugs blew right out of the motor and it had a what looks like a spring around the threads on the spark plug. I don't know much about motors at all and i'm trying to figure out why this could of happened so I can prevent this from happening to me again. I was told that the spring is called a "heathing coil??" and that it has already been fixed once. He also told me it is an easy fix all I need to do is drill out the spark plug hole on the piston put a new spring into the hole and screw the spark plug back in. But thing never go that easy for me and the guy has never even had or used a boat so I would like to get some advice from people who have experience.
Is it an easy fix???
Is it worth fixing???
can it be fixed twice???
PLEASE GUY'S ANY HELP WOULD BE GREAT!
Let me know if you guy's want see any pictures

Re: 55hp Evinrude "Blew up" Need some advice.

I don't have any motors that big or new but are you sure the spring thing isn't just the threads on the head stripped out. The bang could have been a backfire. Does the engine still turnover. If it stills turns over check compression after replacing the head or getting What's called a helicoil installed. As For a new head check eBay or post an add on aomci

Re: 55hp Evinrude "Blew up" Need some advice.

Take it into a machine shop or GOOD marina and have them look at it. The threads may have just stripped out of the head or the helicoil did but they will be able to tell.