[Lee]

Thanks Jac Mac
Those -16 fittings are not moving. They are definitely in for keeps, so it looks like I will have to restrict them somehow. I want a little pressure in there relative to elsewhere otherwise the bleeds at the back of the heads won't work.

Still seems strange why there is a need for 1.5 or 1.75 pipe anywhere in the system when there is a 2 of -12 restriction at the inlet to the block and at the outlet from the heads.

Just thinking about it, the heat in the heads will create additional pressure, or have I got my high school physics the wrong way round?

Thanks again