Distributor Rod off?
 

after building the motor up, I set the distributor timing by hand, but I knew it was off. I bought a timing light today, and when I went to advance the timing, I couldn't fully advance it to all 20 degrees, but yet I could retard the timing more than there were notches on the crankshaft pulley. I think my distributor rod is off by a tooth...what do you all think?