LT1 Optispark/timing issues

[barno68]

I'm no LT1 expert, so I'll just hit on a couple of the basics again, most of which others have mentioned already:



-Do you have a ground from the battery to frame? You mentioned battery to block and block to frame, but didn't see battery to frame.
-Do you have compression? Know you said it was a fresh rebuild, but mistakes happen.
-Is it still cranking over slow? I know some people above ruled out starter, but it may be a bad solenoid. Test voltage going in and coming out of the solenoid...should see 12.6-12.8 from the battery and not more than a tenth or 2 drop coming out from the solenoid. I had this occur on a friend's car last month...turning over slow so I jumped the solenoid and the starter motor sounded good, so then I tested voltage at the solenoid...12.7 going in, 8.5 coming out. Had the starter tested at 2 different parts stores to verify my diagnosis, passed at both places. Bought a starter anyway, problem solved.

The block is an extension of the ground from the battery, I have never seen two ground cables ran off a battery itself. In this case, even if the frame or body had a ground issue (which I have already tested for) the ECM grounds are connected to the block. Earlier I ran a jumper from battery to harness ground and saw no difference and had the same ohm reading.

While I have not put a gauge on it, the compression is good as it is a pain to turn over by hand.

I don't disagree about the starter, although I would question the solenoid being a problem as the battery cable connects to the starter so there would be no voltage drop across the solenoid. I am thinking about ordering a new one, but don't believe it is the reason the car will not fire. It is turning over fairly decently now, but it is still loud while cranking.