Figured we would Check the timing on the 370 the other day, found the marks on the H.Balancer, cleaned it up marked it at TDC, 10, and 20, disconnect the vacuum advance hose, plug the vacuum port, started the truck shine the timing light, is about 20 BTDC ???

Something seems amiss, Is there a spout connecter (or something else)to disconnect on the Dura-Spark Ignition system? pretty sure No Computer on this truck !

was about 60 BTDC with vacuum advance hooked up, 20 BTDC with vacuum advance disconnected, from what I have read supposed to be around 8 BTDC, Anyone got any Ideas on Proper timing methods ?