Need More Vacuum

Fire it up & let it get to operating temperature. Connect a vacuum gauge to the manifold.

At idle, advance the distributor while watching the vacuum gauge. The highest vacuum reading is the maximum spark advance for that rpm. If the idle speed climbs out of range, adjust the idle, and twist the distributor for max vacuum again.

Check the timing, and write it down. If it is more than 15 degrees it will probably ping under load. Test drive it. If it pings, back off 3 to 5 degrees and test again.


B.