Initial timing

Here's what you're gonna have to do. Get a timing light. Set the timing to 2 degrees at idle with the vacuum advance disconnected and that hose from the carburetor plugged. Now with the light on the balancer, run the engine up until you see the mechanical advance stop advancing. Subtract your 2 degree initial figure from "whatever" that total is. Say if the distributor stops advancing at 3500 RPM at 28 degrees, then you have 30 total. Understand? You're gonna have to do it that way, to see "which" distributor is in there and how much mechanical advance is in that distributor. My stock 170 ran its best at 12 degrees initial at idle, but I had to limit the total to 30 degrees. I tried 15 initial at idle, but it ran better at 12. If you have a way to limit the total to "around" 30 give or take, they usually perform better with more initial timing than the factory spec.......but "I" would see what's in the distributor FIRST. It appears it could be several different things, so you're gonna have to find out.