Ok guys I'm back. Sorry but haven't had time to work on the baby lately, but may be on to something...
On the good doctor's advice, I re-adjusted the valves. Started it up for a minute, and I had better vacuum at a more reasonable amount of ignition advance this time. Idling better but still not great.
So I backed the locknuts on the rockers off, put a dial indicator on the valve spring cap, and re-adjusted them again, watching for movement. On cylinders 3, 4, 5 on intake valves, and on cylinder 8 on the exhaust valve, the valves are beginning to open before I even get the locknut 1/2 turn tight after zero lash. Watching the dial indicator, as I go beyond 1/4 turn to 1/2 turn, the valve will drop .035" by the time I get to 1/2 turn tight.
So my thoughts were either rocker studs pulling out of head, or rocker interfering with valve spring cap. Does not appear to be either of these. I checked rocker studs with feeler gage, and don't have any gap between the hex on the stud and the head. Also pulled the rockers off and have no signs of wear except right where I would expect at the tip where they touch the valve.
I'm noticing, as I slowly tighten the nut to adjust these particular valves, just as the pushrod lash disappears, the pushrod will become very tight quickly. The other valves tighten up with zero lash, then slowly start to get more turning resistance on the pushrod, as I would expect.
So do I have collapsed lifters under these pushrods?
And if 4 of the valves were hanging open, how did I not notice any compression drop in these cylinders?
