Hey guys anyone out there have any experience with S40 cylinder heads I inquired an S40from local independent where the mechanic walked off the job with this head in a box mounted the head turned the engine over twice by hand nothing hit but only have 30lbs compression however when valves are closed and I insert compressed air in the cylinder they all hold 125lbs air with nothing leaking in exhaust or intake any suggestions ?????????????

Thanks
Thevolvoman2005