Quote Originally Posted by Fast355
Having run his exact engine, the OEM plug is TOO HOT for that application....The dynamic compression ratio of a stock L31 is too high to be able to run enough timing to maximize the power potential of the vortec cylinder heads. The hotter heat range is likely contributing to his detonation issue. Not to mention the TBI ignition system is setup to fire copper plugs, not iridium or platinum both of which typically require more voltage to jump the wider gap. A properly gapped (.035") set of R42LTS plugs would work well for him.
I have run the same engine both with the O.E. SCPI induction and with TBI as well. And while I disagree with just about all of that statement, I find it futile to continue to debate the subject as your opinion on the matter isn't going to change and arguing will not contribute anything useful to this thread. Let's just agree to disagree and leave it at that.