Here is how I'm aware of it: In 1970, the pistons had less of a dish than the later years. That, combined with a slightly smaller combustion chamber gave the high(est) compression ratio. From 71-76, the piston dish was the same. From 75-76, the combustion chamber was the largest (open chambers). So, if this info is correct, using a 75-6 block with 1971 - 74 heads would get you a compression ratio similar/same as the year of the heads (~8.5). If you use 1970 heads on the 75-6 block, you will fall somewhat in between because you have more of a dish in the piston but a slightly smaller combustion chamber (than the 71-4's). Since the chambers aren't that much smaller, you'll likely be closer to the 8.5 number than the 10.0 number. I hope that makes sense (or is at least accurate). I'm going to be doing a similar thing. I have a 76 block and 73 heads for it. Assuming I just do a head swap, I should get a compression ratio similar to that of 1973 (~8.5:1). I've also got a set of 1970 pistons (from Jim W) that would raise the compression closer to that of 1970, but not quite because I'll have the slightly larger combustion chamber size of the 1973. All of this assumes that the head gasket is the same thickness, no head milling, block decking, etc...
I WAS UNDER THE IMPRESSION THAT BUICK WAS GOING TO HELP OUT RACERS BY BUILDING A BETTER BLOCK AND SMALLER DISHED PISTONS . THEN USING BIGGER COMB. AREA IN THE HEADS. THEN THE RACERS COULD BUY THESE SHORT BLOCKS, USE THEIR HEADS , INTAKES ,CAMS, ETC. I QUESS I WAS MISLEAD.
There are a couple of different block projects ongoing. One is an aluminum block and the other is a cast block. If you do some searching of v8buick.com you should be able to find some of the threads. From what I remember, both blocks are designed to bolt on all the same pieces that the stock blocks did, while fixing all the weak spots of the original design. Neither of these blocks are being done by Buick though.
YES, I HAVE READ THOSE AND I THINK THAT WILL BE THE WAY TO GO. I GUESS I SHOULD HAVE PUT IN THE TIME PERIOD I WAS TALKING ABOUT.:error: THIS WAS BACK IN THE 73-74 ERA. THE SUPER STOCK,STOCK AND OTHER RACERS OF THAT TIME PERIOD ASK BUICK FOR SOME HELP. SO BUICK RETOOLED THE 455. THE BLUE BLOCKS WERE BORN. I DON'T HAVE 75-76 PISTON TO MEASURE THE DISH CC WITH. HAS OR CAN SOMEONE DO THIS.:beer
