what the title says.

 

10.4:1

 

thanks but i mean PSI....i found it. should be 100 minimum.

 

100 PSI min means nothing. Cranking PSI on a healthy motor is around 180. All should be withing about 5% of each other.

 

There is no "correct" answer, but I'd sure like to see 180psi rather than 100psi

Pressure observed during a compression test is dependant on too many things:

-how warm was the engine
-how strong is the batter/starter combo
-how wet are the cylinder walls
-was the throttle body held wide open
-how many crank rotations were used
-did any fuel get into the cylinders
-were all the plugs removed

Probably a few more variables. The important part is how close were the readings from cylinder to cylinder. You are looking for readings that are out of line with the others. Shop manuals will typically tell you to look for no more than 20% variation, but I don't think you wany anything that sloppy for a performance engine.

 

Rocker ratio might even have a small effect.
My 180K mile Roadmaster wagon cranked 195-200 on the few cylinders I quickly checked this has a different cam than the f-body version of the LT1 and larger combustion chambers in iron heads making a lower static compression ratio.