Hissing sound turning engine by hand

[thejollyrancher]

Hey,
Just rebuilt by engine. I replaced all the bearings and piston rings along with a head build. I have yet to throw the cams on there and do timing. I have the bolted down on he block with sparkplugs installed and when im rotating the engine by hand im getting a loud hissing and it gets pretty diffifult to rotate. Sounds like its building some compression. Is this normal?

Thanks

Edit: forgot to add tge bad part. The valves are hissing a tiny bit at the top of the stroke

 

[donniekak]

The valves should not leak at all. Were the valves lapped into the seats?

It should be difficult to rotate the engine with spark plugs installed, and some air hissing through the ring gaps is normal.

 

[thejollyrancher]

I did lap them but maybe not well enough. Ill give them a leakdown test to make sure