[Healeys] Decarbonizing technique?

[Peter Ryner]

I had an uncle who always bought used cars and the first thing he did was to 
put a quart of "top oil" in a full tank of gas to clean the engine.  Worked 
fine until he bought a car with a large amount of carbon build up.  Just 
like someone else pointed out - the carbon broke loose in chunks and broke 
several valves.  The engine had to be totally rebuilt.

If there is a chance of having large carbon deposits in the engine I would 
recommend pulling the head and cleaning mechanically.  When parts were 
inexpensive and plentiful it may have made sense to take a chance.  Times 
have changed and our engines are too valuable to try a quick fix for a sick 
engine.

To keep the carbon down use the car like it was intended - drive it!
My $.02
Pete