i ws being sarcastic about the car blowing bubbles
and if you put anything in the radiator it has to circlelate through the engine to keep it cool
flush it with desial but dont start it

ok about the bubbles... yes water goes through the engine but not in contact with internals like pistons and tappets

In the past we used Swarffega [hand cleaner] to clean or proper rad cleaner.. Drove it 20 ks then flushed...
Use NEW head bolts, check timing. If anything till settled run it slightly retarded .. Say ?? 2* back from normal to reduce combustion chamber pressures till it settles in...

the water will come in contact if the head is cracked or warped coz it will be seeping it in slowly
if its been faced its never 100% if its 98% it will be taking a little bit of water in aswell

dude, lay off the drugs.

a bit of soapy water will do less harm the a chemical radiator cleaner.

if your brother had to have a rebuild after he did it. it's because his engine was already f**k