[6pack] Carbon on top of pistons - engine experts please help!

[Sally or Dick Taylor]

 Greg----I have also read at least one article about the results of
"steam cleaning" the combustion area. Since I already have a working
water injection system, I gave it a try. I was already going to do a
rebore, so any damage that might have resulted from breaking loose the
carbon could be later dealt with.
A mixture of soapy water and isopropyl alcohol was run thru the intake
manifold until the pump had emptied two quarts of water. (About 5
minutes with my injection nozzle) This with an engine speed of around
2,000rpm.  Lots of dirty water came out the exhaust pipes, but when
later removing the head, found the piston tops to be firmly holding onto
elixar of carbon. 

The only way I would now believe this process to work would be to see a
"before and after" look at this area.

I will admit that I never did have a run-on issue, so it could be that
this process could remove some sharp corners that were holding carbon.
So far as cleaning off the pistons tops...nope!
 
Dick

Greg wrote:
I was re-reading an article printed in a club newsletter from the
distant past about an old time mechanic who recommended water injection
to eliminate this problem. His technique was to remove the air cleaner
assembly and use a pump-up garden sprayer and spray water into the
carburetor while the engine was operating at 2000 RPM. The premise was
the steam generated by the water would clear the carbon from the piston
tops. The amount of water was regulated as to not stall the engine. He
reported that after this treatment the run-on problems were gone. 

Does anyone have any thoughts to the validity of his actions? 
Greg Gelhar
1973 TR6
______________________________________________