I have a 95 talon esi which I boosted with stock motor running at 8psi and had it that way for about 7 years. I finally decided to get the engine built with forged piston and stronger rod etc.
Motor is built and installed it in the car. My first initial start up was good. Used engine break in oil to ran the car, bled the coolant, fans came on and it was good, let it idle for about 1 hour or so and had to shut her down because it was already late.
The next day I drained the break in oil and put in regular 5-30 synthetic oil started the car and it was good and was letting it idle for about 10mins. Then all of a sudden the car starts to sputter and tons of smoke coming out the exhaust (that heavy lingering smoke) so I shut off the car. Let it cool down tried started it up again and the same thing.

I performed a compression test and readings were 30-215-215-215. I put a cap of oil into the cylinder 1 and the pressure went up to 50psi not much of a difference.
So decided to do a leak down test on cylinder 1. I add the pressure to the cylinder and there is no leaks the pressure is holding perfect. Rotate the crank and reset and try the test again and again no leak.
I decided to try the compression test again. This time during the compression test while cranking it wasn't creating much pressure again then i heard a pop sound and the compression went up to 215psi. So i tried the test again and back to 30psi.

I'm really confused here and not sure what the problem is. I'm thinking the problem might be the head and that the exhaust valve isn't seating properly. Forgot to mention that when i pulled out the spark plug it was completely clean and when looking down the plug hole i can see the piston face was clean as well compared to the other plugs and piston faces.

Need some help and hear what you guys think as i don't want to redo the head and its not a head problem.
Sorry for the long story.
Thanks,
Dave.

If it was a valve problem you wouldnt be getting that much smoke out of the exhaust. Sounds like a ring problem. I would start by pulling the head and the piston out of that cylinder. Could be your PTW clearance was to tight or the ring gap wasnt large enough.

I've posted on some other forums also and everyone has the conclusion.
thanks for your input.