The Flat top has a 0.55" Compression Height. The Non-Hemi dished piston has a 0.57" Compression Height. So you loose 0.02" with the flat top but make up 0.040" with the rod.
So your piston, at TDC, should be 0.020" Higher up in the cylinder than it was with the stock piston and rod.
Assuming you were originally 0.020" In the Hole, your piston should now be flush with the deck. If you were 0.035" In the hole, now you are 0.015" In the Hole.
Anyway, my best guess is 8.75: 1 to 9.0:1.
But depending on where the piston sits in the hole, you might be able to use a 0.027" Gasket and bump that up to 9.5:1.
---------- Post added at 09:29 AM ---------- Previous post was at 09:25 AM ----------
Doh!
I knew someone was going to ask me that.
You're going to blast me for my answer.
Any forum posting I've read has seemed to indicate that their non-hemi Predator was "in the hole" before modification.
(I think typically about .02 which probably is just a rounded version of your 0.015)
I made an assumption.
(wince)
The NR site seemed to pair this rod with that piston and since I didn't go to a thinner gasket I figured it should be safe.
Both of my Hemi's were around 0.025" in the hole stock. I think Non-Hemi sit a little lower in the cylinder, but not really sure. Never had one. I, like you, am going off of what I read about Non-Hemi deck Height. I think you will be fine. Probably even with a 0.027" gasket. I don't think you will be popping out with your set up, But always best to check.
