The 670 is an excellent head, as long as you use a dished piston to adjust compression for the fuel you plan to use they are great. Saw a test where the open-chamber mod enhanced flow on the bench but made no real noticeable increase in power, go figure!
Supposed to be one of the best if not THE best flowing head at low valve lifts (under .400") in stock form. I have set I'm saving for a 350 build-up someday, they will be right about 9:1 compression on a 350.
Let's go racing!
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