I would put in the j12yc plugs, run your vacuum line to full manifold vacuum (use the vacuum port on the intake manifold) and cap off the port on the carb, temporally block off the vacuum line at the vacuum advance and set the timing to tdc or maybe even 2 or 3 degrees advanced to start, then reconnect the line, readjust the idle and mixture and see what that does.
Thanks Mike.
I tested the vacuum on the carb port and I'm getting 13 hg when idling. I will check the vacuum advance diaphragm tomorrow.
I looked earlier but didn't see a vacuum port on the intake manifold. Where is the vacuum port located (it probably is plugged)?
I can check and adjust the timing next.
