IT SEEMES THERE IS A LOT OF BAD INFO FOR MELS MAYBE BECAUSE OF ANGLE DECK BLOCK??. I ORDERED A SET OF NEW FORGED PISTONS FOR MY 59 430 REQUESTING 10:3 - 1 WITH 042 HEAD GASKET. I'M ONE OF THOSE GUYS WHO BELIEVES LITTLE AND CHECKS EVERYTHING AFTER INSTALLING ONE PISTON AND CYL HEAD WITH USED STEEL SHIM - 020- GASKET AND CCing TOTAL VOLUMN [100 CC's] IT WAS ONLY 10;01 - USING RULE OF THUMB EACH -010 change = .1 RATIO DIFFERENCE THAT WOULD LEAVE ME WITH APP 9:8 WITH THE 042 COMPOSITE HEAD GASKET. I RETURNED THAT SET. I DECIDED TO CHECK EXTRA STD BORE 58 430 WITH USED STD EDJ STOCK PISTON AND WAS VERY SUPRISED IT HAD 110 CC's WITH 020 GASKET THATS APP 9.2 !!! AND NO IT DOESN'T HAVE A BENT ROD OR OTHER MECH DEFECT WHAT HAPPENED TO ADVERTISED 10:5 RATIO. AM USING 59 FLAT HEAD NOT LATE MODEL WITH 8 cc.s CHAMBERS. MAYBE THIS IS WHY MANY AFTER MARKET PISTONS LIKE EGGE HAVE LOW COMP RATIO - THEY COPIED THE STOCK PISTON SO HEY GUYS BUY A CC BEAKER -SPEEDWAY HAS THEM AND RECHECK TOTAL CYL VOLUMN [WITH GASKET AND HEAD ON]YOU MAY BE UNHAPPILY SUPRISED
I USED THIS FORMULA TOTAL COMBUSTION AREA + CYL VOLUMN
---------------------------------------------------- = RATIO
TOTAL COMBUSTION AREA
ALSO TO CONVERT CC's TO CUBIC INCHES CC's
------- = cubic inches
16.387