i have a 79 k5 with a 73 307 cid chevy engine ,i was going to set the timing ,it needed advanced a few degrees but after i loosened the hold down ,actually ended up completely removing the hold down and the nut the distributor wont turn either direction i saturated the base of the distributor for 2 days with pb blaster and tried again today to turn it still wont budge ....please help

 

Sounds like its in there good. Have you tried putting a pair of channel locks on it?

 

yes ,it wouldn't budge