Removing carbon from combustion chamber.

[Mickey H]

Hey all, currently rebuilding an engine, has excessive carbon buildup on both the piston surface and the combustion chamber. What is the best way to remove it?
I've tried carby cleaner with a wire brush and drill, but don't want to risk damaging the cylinder head surface. Is there a certain chemical I can use to make it easier? Here's a picture so you can see what I'm talking about.

[Billzilla]

Just take it to a cylinder head shop, they'll drop into a tank of cleaning fluid overnight. It'll cost bugger-all.

[MWP]

Subaru Upper Engine Cleaner.
Go to you local Subaru dealers parts counter to buy it.
Does the job very nicely.

[mattysshop]

General purpose thinners and a plastic bristled pot scrub brush from under your sink

but as Billzilla has stated most engine shops can just drop it in the caustic hot tank for a cycle...

[Grippy]

Oven cleaner does wonders mate, dont leave it on long though.

[TERRA Operative]

Not good on an alloy head though. The caustic solution is very fond of eating aluminium......

[DrNick]

Stuff like that I would remove the valves and clean them up using a brass wire wheel on the bench grinder. Be very careful not to scratch the valve stems though.
The stuff in the combustion chamber comes off very easily with throttle body cleaner and maybe a touch with the brass brush too, but its not baked on like the scale on the valves.

[Vios-GT_07]

Subaru Upper Engine Cleaner.
.

first thing that came to my mind but how do you apply this with the head off??

i tried it but all hell broke loose and it became very messy...

Oven cleaner does wonders mate, dont leave it on long though.

safe for alloy heads? have seen chemicals make the surface become flaky.. is that because of leaving it on too long?