I have a 93 Z that I just rebuilt the motor in. Stock internals - it just got a freshening with new rings, seals and misc. I have the Lt4 hotcam kit and self-ported heads. I have mac headers with no cat has well. Upon start-up it smoked white smoke real bad but then stopped after 2 or 3 minutes. It did not smell like anything at all. I broke in the cam for 20 minutes at 2.5K rpm's then I drove the car somewhat easy for the first 100 miles. I currently have 100 miles on it know. The question that I have is that when revved to about 4K rpms, it puffs out a could of white smoke. Sometimes it is a large cloud and sometimes barely even noticable. I have not taken it past 5K yet becuase the motor is fairly new. When driving normally around town I do not see any smoke at all. I can smell a little bit but not hardly at all. The code in the ECM is 23 for a mat sensor. I am sptting out a lot of soot and eating up gas like crazy. I know it is running very rich. The car is also hesitating a little when taking off (It is a M6). I just pulled the plugs (10 minutes with Mac's) And none of the plugs had excessive oil on them. Only 3 plugs had a little trace of oil. The rest are just pretty carboned up. What should I do know? Can the smoke be from the car running rich (I doubt it though). I did not hit any water jackets in the heads and obviously replaced the valve stem seals when I put the heads together. The valve guides did not seem worn and the valves where not worn at all. The car did not burn oil before the rebuild. It does not seem down on power but I have yet to really hammer on it. What should I do next? I did notice the o2 sensor connector is melted on the header though. The smoke does have a oil smell to it tough. Can I do a leakdown test to check the rings or valve guides/seals? Is that possible. Thanks in advance, I really need the help. P.s. all bottom end clearances where in spec.

 

Kind of hard to read your runon sentence there

Have you checked coolant level? Thats the most obvious one that jumps out at me, head gaskets. There could be a couple reasons for that.

 

Coolant is full and not low at all. I pulled the dipstick again and it seems to have lost a 1/2 quart in the last 100 miles. I just noticed the problem with the low oil. What kind of test can I run to verify the heads or the rings?

 

Leak Down Tester...

 

I am going to test it on sunday. I am going to try to fix the fuel problem first.