I'm about to start putting my engine back together. Just wanted to get opinions on what size to gap the ring. I have Darton sleeves and CP Pistons. Plan on running around 30PSI on E85.

 

Your pistons should had come with a spec sheet telling what every ring gap should be depending on your application. Its a bit complicated going from metric to SAE so just make sure you don't get confused. Honestly its something I would just pay your local machine shop $50 to file and gap all your rings if youre not sure what they should be or have any doubt in your mind.

 

For reference my rings are gapped to the following. Keep in mind every manufacturer is different and depending on your intended use gaps will change. I would suggest for you with a street car follow the Moderate street turbo.

Formulas based on Arias Specs.

High Performance/Street-Strip Compression Ring (Bore x 0.0045) Second Ring (Bore x 0.0050) Oil Rings (Min. 0.0015)
Moderate Street Turbo/Nitrous Compression Ring (Bore x 0.0050) Second Ring (Bore x 0.0055) Oil Rings (Min. 0.0015)
Late Model Stock Compression Ring (Bore x 0.0050) Second Ring (Bore x 0.0053) Oil Rings (Min. 0.0015)
Drag Race Compression Ring (Bore x 0.0055) Second Ring (Bore x 0.0057) Oil Rings (Min. 0.0015)
Nitrous Race Compression Ring (Bore x 0.0070) Second Ring (Bore x 0.0065) Oil Rings (Min. 0.0015)
Alcohol/Blown Race Compression Ring (Bore x 0.0060) Second Ring (Bore x 0.0060) Oil Rings (Min. 0.0015)

Example: Your piston size 87mm = 3.4252"
Don't forget to add your piston to wall clearance if going off piston O.D. which should be around 0.0040-.004. (I did it this way since I have to estimate my final bore size when its not in front of me) Proper way is to get a dial bore gauge and measure every cylinder and do every set of ring gaps to every cylinder size since they may differ slightly from one to another.
So 3.3292 x 0.0050 = Compression Ring Gap 0.0166"
3.3292 x 0.0055 = Second Ring Gap 0.0183"
0.0016 to 0.0017 = My recommendation for oil ring gap.