BE CAREFUL which pistons you use ....

I had 1970 TRICK SHORTBLOCK go together with the EARLY PISTONS !

Now if only I had had DECKED the block and had a decent set of 915 heads ...

Something is not quite right in your math. The IC687's net 4.5 cc volume above the 2315 flat top will be 0.4 increase in compression.

Like Lew stated, or was implying, watch your head volumes and gasket thickness. You'll be better at 9.2 or 9.3 verses risking detonation with 9.6 or more, IMO.

Also, if you are on a budget, you can probably use the 2135s without balancing the assy, the IC687 you will.

There are posts-one very recent from myself here about great power from smog era OEM pistons. In this case it was the smogger 360. Several members here are running in the 12s with the deep down in the hole factory mopar pistons and a good but not radical cam. with a good round bore with great seal - Id just use the lower comp piston unless your goal is greater than 12s?

i don't remember the exact numbers but I think the compression ratio for the 383 I did with the 2315 pistons was 9.1-9.2. I wasn't sure they'd work with a non-quench but they did. overbore sizes are heavier than stock and I wasn't sure they'd work without a re-balance but they did fine; smoother than my balanced 440. down sides to the 2315's are no valve reliefs and weight. only down side I can think of for the icons is noise when cold. I use a set of icons in one 440 I have and they're pretty noisey cold but that's just the nature of a true performance piston.

Just for a data point. My '69 roadrunner 383 had stock pistons 0.010" in the hole. The 2315 pistons are now 0.022" in the hole.

Since this old thread was dragged back up and I was not on the board much back when this was posted let me chime in ...

I have looked at this subject a lot because I have raced pure stock drags with my 69 383 GTS and planned to do the same with my 69 3383 Superbee .

Stock 68-69 HP compression height is 1.932, in a CHRYSLER BLUEPRINT SPEC deck block with a Blueprint spec crank stroke and Blueprint spec rod, the piston sits .0025 in the hole. ... this is not the same as NHRA spec which is .020 ABOVE the deck which is what Chrysler tells them and is not actual factory production spec.

KB pistons are 1.908 and the 2315 is 1.920 , Diamond also has a piston which I think is 1.915. I never measured, or looked into, pre 68 or 70-71 because I had no interest in them.

The aftermarket doesn't make a 68-69 piston because they make a one size to fit all years of 383 production, the 2315 is the closest to 68-69

That says your deck height was .0075 over factory spec . I know it's too late know but you could have had the block decked by a shop that uses a machine like a Rottler CNC for decking blocks , that can stop shy of the the numbers and move up and down at the stop point to finish the cut square... I've had it done to a couple of 383's

I was able to get the CR I wanted (9.0:1) without decking the block.

That's good but my reason for decking the block is that after thousands of heat cycles the block has settled. I take one rod and piston combo and put it in the 4 corners of the block and measure how deep the piston is in the hole , it is NEVER the same side to side or front to back. I usually pick the deepest pick a corner and when the block is cut the cutting confirms the warpage that has occured. For a mild street build what you did is just fine ... it's what most people do ... I'm building for zero deck and a certain squish/quench number so I spend the extra time and money.