SBC timing at idle "walking" .. actually steadily climbing

[bessie66]

Hey all,

truck is: '71 c10 350/th350, eddy performer intake, headman headers, ngk plugs, holley truck avenger electric choke carb, HEI dizzy, etc

Issue is - i noticed shortly after installing the holley carb, that the timing at idle steadily increases as it warms up. The rpms climb to the point where it'd be violent if thrown in Drive. The timing will increase until I kill it. Initial is set at 10(with vac adv disconnected), yet i've watched the mark increase to 16-18 before i decided to shut it down, otherwise it will continue to climb as it runs.

Anyone else been blessed with this occurance?

Thanks y'all.