Today's update.
I took it out for a 0-60MPH run, first time since setting the timing way up to 17 BTDC. Each run was under 20 seconds! A couple of backfires, hesitation still at moderate acceleration. I know it's running rich, likely needs smaller jets.
I also did a compression and leakdown test. In all cases, I couldn't hear any hissing from the carburetor or the exhaust, but plenty from the valve cover meaning the rings. To confirm that it was from the rings, the first cylinder I did, #1, blew smoke out of the valve cover. Cylinders 1-4 aren't that bad, 5 is worse, 6 is the worst. The manual says compression should be 130, so they're all a bit low.
Cyl, Compr, Leakdown %loss
1, 105, -14%
2, 105, -15%
3, 108, -17%
4, 110, -18%
5, 105, -26%
6, 100, -40%
Looking at the plugs, 5&6 look the best. Maybe the valve seals are leaking the least, maybe they're just the hottest cylinders (typical from my limited experience). #4's oil is the worst.
Looking at this, it seems that 1) valve seals are bad, 2) valves look to be fine, 3) rings in two cylinders were noticeably worse than the others, 4) compression is a little low all around.
Bottom line: rings/pistons need work in addition to valve seals.
Your thoughts are always appreciated.
Mark
