Combustion chamber cake?

[randy]

I'm in the process of a valve job on Swamp Thing, I knew I had a valve seal problem years ago but just getting around to it now. Plenty of oily carbon all over the place, but there's also a hard brown cake-like deposit on the piston crowns. I was wondering if any of you know what that deposit might be caused by?

[xschop]

cake

if you can hold out a few more million miles, you'll have a nice diamond form in that muck. Just superheated hydrocarbons, probably from extra oil deposited from the seals...my2cntz

[Snow]

You can try placing a rag soaked in vinegar on the valves and pistons to break down the carbon without damaging anything.

[xschop]

chemicals

I like to use methylene chloride for carbon buildup or old paint removal. It is the main ingredient to the aircraft paint remover you find at wal-mart....wear gloves and goggles....then you can brush it off and then shoot carb cleaner to take it to spotless....jat

[randy]

Gentlemen,

It's not the removal, but the cause that I was asking about.

[Snow]

Originally posted by randy
Gentlemen,

It's not the removal, but the cause that I was asking about.

We know that, we are just trying to get our post #'s higher

[DiverRay]

Randy,
If it's brown, it is from the gas. some brands have additives that build up quickly, and others will keep the combustion chamber clean. I've found over the years that ALL Shell gas will cause the buildup MUCH faster than other brands. It's great to bring up the compression on an older engine, just don't get it too hot. IF the carbon buildup gets too hot, you will have a BAD knock and pinging from the mixture exploding too soon. I try to spray a little carb cleaner into the carbs at tune up time. it keeps the build up down.

[prometheus578]

The build up is mostly the burnt oil. (at least in your case)
I agree with Ray about the additives. Additives will also color your sparkplugs funnily, too.

[mason79]

hey, will part of a bottle of chevron techroline every now and again help keep the chamber deposit relatively free?

they show before and after pics and i think mercedes or porsche recommends it, any comments of experience?

me and planedick tunne my bike up over the weekend compression 170 across the board, valve in spec, tad tight on the ex side.001, carbs a little off snyc, timing close, runs great with idle screws 4.5 out, maybe the coils, chambers a little black...

[TopCatGr58]

Mason,

Techroline as well as Sea Foam are both highly recommended for periodic maintanence of the carbs, and I'm pretty sure they assist in keeping the combustion chamber clean as well!
T.C.

[mason79]

thank you,

Top Cat