[PeteF]

I don't have the cam specs, but the first owner told me the compression is 9.5:1. I checked vacuum with and without PCV, no significant difference. Also adjusted idle trim screws to maximize vacuum. I'll try advancing the timing as you suggest, to see how high a vacuum I can achieve. The pyrometer is a good idea also, I have one, but I think it maxes out at 250 degrees or so. The ignition is a standard Mallory Unilite with vacuum advance, but I checked vacuum under the carb with and without the advance connected. Thanks for the help so far. I feel like I have an intake leak somewhere, but this has me stumped, since I didn't make any changes and that's a lot of vacuum to lose.