A couple of weeks back I posted that our car suddenly started missing, running poorly, lacked power. Of course, adding to the confusion were the following facts: - my son swapped out the MSD 6AL for a 6+, preparing to setup nitrous injection and wanting to use the timing retard feature available in the 6+ - he actually drove the car home from storage; I had not driven it yet this year when it was running properly; so while it seemed that the problem started when he switched the MSD box, I could not be sure Further symptoms were confusing: the initial timing was around 30-35. Yes, initial timing. (probably should have been in the 15-20 range) and it was fighting itself when cranking, which it never had done. To try to diagnose the problem, we swapped in the original 6AL MSD ignition box, with little to no improvement. Did the following: initially a compression test on 7 of the 8 cylinders. the last one was too difficult to access. since then we did a leak-down test on all 8. all were between 2-4% leak-down when cold. good there. Pulled the timing cover. there was 1/2 - 3/4" deflection in a previously tight double roller chain. ok. a little odd for a 2000 mile engine. put in a new chain. Then we found this - which I'm 99% sure was the real problem: the + and - were reversed between the magnetic pickup on the distributor and the MSD ignition box. Certainly my son modified that wiring when he swapped the boxes. I know that it was correct originally; I even told him to be careful to get those correct. verifying with the tech info available at MSD, they state that definitely swapping those wires will cause timing issues by approx 20 degrees. sigh. I wasted a lot of time tracking this down and I suppose that I should have caught that sooner. oh well. at least we have a new timing chain.