Piston and valve contact.

[mlinder]

Good luck with that. Many times, when you remove the head, you disturb the cylinders enough to break the seal.

.

And many times you don't

[niclpnut]

I figure since it's a fresh rebuild and the engine has not been run, it will probably be ok.

But we shall see.

[Steve]

And many times you don't

That's why I said "many times" and not "every time".

.

[sparki]

like yer say... fresh build should be fine.....