compresion drop, any ideas?

[Foxmxrcer]

ok so i posted a while ago about my 87 shelby Z TII... compresino readings were
1- 119
2-123
3-120
4-90
i finally got my buddys csx out of my garage and the daytona rolled in, pulled the engine and dissasembled it.. the headgasket was fine, it was sealed real well seeing as it was a PITA to rip the head off, none of the rings are broken, no holes or cracks in the pistons, and from what i can see, the valves all seat fine.. only thing i noticed is the infamous crack between the valve seats on cyl 2 and 4. anyone have any other ideas what could have happened?

[4Daytonas]

Too late now but you should have leaked the engine before disassembling.Oiled the cyls for ring test.vac for valve leaks.difficult to diagnose now that it's apart.

[NAJ]

+1
Cylinder Leak Down test should have been done before disassembly.

[tryingbe]

Rebuild the engine while you have it apart.

[IROCNOROLL]

Quote:

Originally Posted by tryingbe Rebuild the engine while you have it apart.

+1. Have the head leak checked and valve grind / guides / resurface done. Check the block for taper and wear and a flat deck. Check the pistons for collapsing. Check rod pin bushing condition, etc. You in there after all.