34 timing is 3400 rpm without advance in park. Runs great without the vacuum advance. I’ve hooked light up to it when I hood the vacuum advance up. As soon as I hit the throttle with the vacuum advance hooked up it starts pinging and the timing mark shoots off the light to the right. Timing at idle doesn’t change
Sounds like the vacuum advance needs to be adjusted. I think someone has it adjusted so that as soon as it see vacuum, it gives full advance. Try adjusting it and see what you get.