I have a fresh 360, 11:1 compression, mild roller cam, magnum heads. kb107's with rings gapped to 0.032". I have about 500 miles on it so far, but driving it every day. I took it out last Saturday to an autocross event and ran a few laps. One of my buddies noticed it smoked a little at idle. The next day, Sunday, I pulled the plugs and ran a compression test. 190-195 on most cylinders, #5 was a little lower than the rest but not anything crazy enough for me to remember (I can go find where I wrote it down if I need to). Sparkplugs all looked good, no fouling. It's only smoking at idle, warm, only under vacuum, and it is oil smoke. Starting cold, nothing. Driving around, nothing. I'm guessing pcv, but is there anything else I should look for? Valve seals would cause more smoking range I'd imagine. I'm still driving it, if it's bad enough to foul plugs I figured I can narrow it down to a single cylinder if it's something more. I'm thinking about plugging the valve covers and putting a vacuum gauge on the dipstick to see if the excessive crankcase pressure or vacuum. Autocrossing may or may not have caused it, that's just when I first noticed.