Anybody out there that can tell me what my compression would be on a 406 w/22cc dish pistons stock deck height with vortec heads?

The key to this is to take cylinder volume ((bore/2) squared), times pi {3.1416}, times the stroke. Convert to ccs by multiplying 16.4ccs in a cubic inch. Add piston relief (or subtract pop-up dome) volume to head deck clearance, head gasket and combustion chamber volumes to the cylinder volume. Then divide that number by the total volumes of the piston relief or dome, deck clearance, gasket and combustion chamber volumes.

Stock deck clearance typically varies from nothing to .030 so you need to make assumptions or go measure. Head gaskets vary from .025 to .050, give or take a little depending on  type and manufacturer. Piston volume you have. Vortec heads run from 60 to 67/70 ish ccs, the factory claims 64 ccs.

Without actual measurements, the best you can do is high side+lowside/2 and get an average.

I currently have a 406 with Dart Iron Eagles and just had a set of 30cc dished pistons. My head volume is 64cc and with the 30cc dish pistons the compression was around 8.8 or 8.9. I sent back the 30cc's in exchange for the 22 cc's. With the 22cc's pistons in the 64cc chamber the compression is up around 9.6 with a .024 gasket thickness, however changing your gasket thickness up to a .039 gasket will reduce the compression to around 9.2:1 . Also this compression is with a deck shaved down .006 in. Hope this helps. There are plenty of compression ratio calculators on the net.

-Mark

I have a 406 with 492 heads (64cc) and a 355 with vortec heads, both with flat tops with roughly 10.2 cr. they both run GREAT on 93 octane. Ditch the dish...  

These are Iron Heads if Im not mistaken.? Are you running a very large cam? I dont see how you are able to get a 10.2 on iron heads and still run pump gas unless your runnin a very large cam. Thanks for any info.

-Mark