I tried the longer wires on 1-6 & 5-8 and there was no noticeable change in the number of misfires. At idle the advance was 15.5 deg and would go to ~ 31 deg at 2500 rpm. My reader has shown 0 deg knock retard from the start, so I just assumed it was not able to detect this PID... or maybe there was no timing retard happening... just not sure.Take two of those "not long enough" HEI wires and splice them together end-to-end. Put a couple of layers of tape over the splice and route/tie the long wire so that the splice is several inches away from any ground.
Do you see any difference in the knock-retard events in live-data now? I would be looking at both the frequency of occurrence and amount of retard.
Correct I swapped injectors and the problem did not follow the injectors originally from 6&8 and 1&5.I doubt, then, that this is an ignition problem. Not the plugs, coils, PCM, or ICM (if it has one).
As I recall, you have swapped injectors too, with same results, problem stays primarily with 6 and 8; correct?
So, I am suspicious of valve operation. I would take off valve covers and check valve-train visually, and try to measure lift on valves for 6 & 8. Precision not required, just to the nearest 1/32" will be good enough.
Also, a simple vacuum gauge may give some clues..
Oh, I forgot about the EGR. RA does show an EGR gasket, did you see that? You can't rely on RA listing all parts. If this engine doesn't have VVT, then I would expect it to have EGR somewhere.