This is weird. My idle has been getting progressively worse over about the last month. This week, I noticed some knocking when I would let up on the gas for the 1-2 shift ("hey, who has the diesel?"). My guess is that when I closed the throttle the vacuum went up enough to stack some vac advance on top of the mechanical advance and put it into knock land. (I was planning on figuring it out this weekend and driving the car, but the fuel pump in that quit yesterday and so...) When I hit it with the timing light, I was at 45* BTDC at idle. /forums/images/graemlins/confused.gif Unplugging the vacuum dropped it back to about 15*. My vac can was giving me 30 degrees! I have no idea how this came to be. When I set it all up a year or so ago, I had 14* initial, 20 degrees mechanical and I thought about 15 from the can. This is the Crane adjustable kit. WHat confused me is the vacuum limit cam. This thing doesn't limit the maximum vac advance, but the minimum vac advance. It holds the thing activated slightly. However, this can still be used to limit the amount of vac advance by setting the cam and then retarding the initial advance back to where it was to begin this. In fact, this is necessary since setting the cam is like always having a little bit of vacuum advance present. The end effect is the same, because increasing the minimum will reduce the total range of vac advance available, but this takes a lot more steps to get everything set right. Has anybody else run into this? Is there another way to use the limit plate? The idle is smooth now and no knock. /forums/images/graemlins/grin.gif I just wish I knew why things have changed.