906 mopar heads cc 5. With that said, both can have the larger valves installed and have the bowls worked to perform equally. All the uncut open chamber factory heads I've measured (906, 452 etc) came out right around 90 CC but usually they vary and have found heads that vary on the same head. Got a question for the gurus. 1. This CNC machine work doesn't only Any idea what the backwards upside down B and 1 are for? The '906' heads were the standard head casting for all RB and B engines from 68-72 (ish). If you're using a clear plastic plate to seal the chamber, you could have two holes in it. The only way to be sure is to measure it though. The cam, crank, pistons, etc are what made the differences. The only positive about these heads were they cc’d to ~84ccs and knocked the compression down to make it a little more street friendly. The comp ratio is about 8. 060 along with the Starting with factory 906 castings, Muscle Motors completely cleans and inspects the heads before treating them to their proprietary CNC porting. 060 off you will have around 79 cc chambers. Every 906 head that I've checked (many), no factory heads were ever over 90cc or less than 87cc unless they were milled but I'm sure there are some that are over or less. The later heads were more like 90 + CC's. Are these better than the 906 heads that I have? Would they be worth some head work on them or should I hold out for some 915 or better? From what I have seen, the 915's will increase the compression almost a full point, but have port flow issues compaired to the 906's. Are these better than the 906 heads that I have? Would they be worth some head work on them or should I hold out for some 915 or better?. They are good heads and were used on everything from 383 2-bbl engines up to and including the 440-6bbl engines. I also use transmission fluid. I wouldn't pay someone to cc them for you because that can be done easily at home. Never noticed a big difference in the rocker stands. A buddy of mine has offered me a set of 516 close chambered heads for free. The piston looks ok but I would much rather swap out these heads for something reliable and maybe more reputable. I had at least a couple dozen 906 heads. No difference in the heads. 020. Good luck. From what I have seen, the 915's will increase the compression almost a full point, but have port flow issues compaired to the 906's. One for fill and one to let the air out. 060, what are my CC now? I have a 73 440 with . Milling 906 heads . Some heads vary within the same head88-90cc so all the chambers should be checked. with steel shim head gaskets that when compressed are about . After shaving . Stock 906 heads had 89 cc chambers. 040 over 2388trw flat tops and 906 heads. I just had the heads milled . The chamber CC's were generally 86 -88 CC. cbaog effuu teinf fzlsya tsgkic lekkrs iybvi zing fleog fagns