Weird Hot Knock??

[Brandon_]

so i picked up another 95 gmt400, and it has the 5.7l motor in it, after about 2 to 3 hours of driving it would start to knock, i parked it and let it sit, then i drove it again for about 6 hours let it sit idle and all that fun stuff no knock this time, could it be a bearing on its way out, oh plus it has a bit of a missfire

 

[90halfton]

Did it hold oil psi? Fuel psi? Is the timing right ? Does it have oil in it ? Lol

 

[Brandon_]

Oil Psi on a mech Gauge is about 30psi at idle, and oil is at the top of the hash mark, i just was out in it and it knocked shut it off let it sit now it won't start but its blowing black smoke while trying

 

[90halfton]

Hmmmmm. How do the plugs look? Timing? Have you checked fuel psi?