Ignition Timing Off by 2 Degrees

hey guys. rebuilt the head and put everything together. when i went to reset timing, which was at 4 degrees BTDC, the distributor would not move any farther to advance timing. it says it should be set at 6 degrees BTDC. if seems to run ok, can i leave it at 4 and be in ok shape? thanks

did you use jumper wire or disconnect vacuum hoses?
if you did and its turned as far as it can go you may have belt off one tooth