Engine Builder questions

[GoDadGo]

Thanks for the replay all. I am not sure if it's a misfire, piston slap or some other anomaly. I am going to drive it some more and the car seems to like a lopey idle but I am going to go see my chassis dyno guy and have him look at it. It's in a narrow part of the band. The engine seems to be happy as can be 800 through 6000... any other ideas?

What is your initial timing set at?
Could your timing be a little too far advanced causing the initial ignition to make the piston slap at 700-750 RPM?
My car idles well between 850-900 RPM and I'll hear some knocking and/or slapping when idling way down at or around 750 RPM.
You're running a much higher compression than I am with similar cam specs so this may be the issue.
Good Luck & Have A Very Merry Christmas Which Just Started Tonight!