Don't have a clue what 68 is talking about, what I gave you was a test of the diaphram. Ok now that we know you have vacuum advance do the test I gave you. If the timing advances with the vacuum pump you can adjust your diafram with an allen wrench by inserting it in the vacuum line hole. Adjust it to come in earlier. I'm sure if you do a search on this site you can find what size allen wrench and which way to turn it to come in earlier. Be careful about drilling holes in your plates. It's not easy to undo and in all the engines I've built I've never had to do that.