How do you sit the timing on a big block Chevy?

Answer 1

Use inductive timing light. Clip timing light leads on batt & no. 1 wire. Keep wires out of the way of fan, etc. Let car idle. Point light at balancer & pull trigger. It will flash when no 1 fires. See where the line on the balancer is in relation to pointer on timing cover. This will tell you where timing presently is. It should be a few degrees advanced. IF you need to change- Loosen clamp distributor just enough to allow it to turn. (no more or it will hop & may have to reinstall-when running, cam gear pushes them up) Keep wrench handy. Use the light again & turn dis. slowly while running& you will see timing move as well. When it is where you want, tighten clamp.

You need to check initial-at idle

Total-with vac advance opening plugged at around 3k rpm (when it's all "in")

Total with vac advance operational. This way you can check total advance including mech & vac & see if both working. You should check recommended initial & total for your engine. They tend to like a lot of initial, but that effects your total & you don't want total to go too far beyond 40 degrees or you get nasty preignition.