I've been reading and searching on this board for a few weeks, hoping to find a solution to a smoking problem at start up.'77 z engine, bored .020" with flattop pistons, slightly hotter streetcam,Clifford 4V intake with Holley 390 carb,headers and 2 1/2" exhaust.Engine has 4000miles on it and just started with blue smoke at start up. never while running. Compression either hot or cold is 225-230lbs on all cylinders, initial compression stroke is 125 on all cylinders.head was redone at rebuild with new valves,and seals...guides checked out Ok. About a month ago, I found a broken guide on #3 exhaust and thought that was the problem. Head was pulled and redone all new guides and seals were installed, Head was checked and had 0 leakdown. Reinstalled head and still had same problem. Leakdown test, with Snap On dual gauge tester, on cold engine showed 0 leakdown on 4 cylinders and 1/2lb on two cylinders. Carb was rebuilt and checked for leakage,PCV cleaned and checked,no sign of coolant in oil or vice-versa,brake fluid not being sucked into intake, intake shows no sign of oil contamination. Ignition checked, wires metered.Running 20-50 Castrol oil...no usage Everything appears to be perfect in this engine. Yet, it still smokes at startup. I'm pretty much out of ideas.Hopefully someone can help. Sorry for the length. Thanks in advance!