Stopping the knock: Lower compression and ported heads...

RustyRatRod said
You've never had any of your distributors apart to limit the advance. Not one. You think we're talking about the springs and we are not. You cannot half *** this stuff. You have to disassemble the distributor and weld up at least one of the advance slots to limit the total amount of advance. The reason is because the engine requires so much initial timing that without limiting the total, you will have dialed in too much total from having so much initial. You've never done that. You're doing it wrong.

Sorry Rob, but you may not be remembering this right.
The 2 MP distributors that I have here are essentially Mallory distributors. welding up the slots isn't necessary on these 2. The baseplates have Torx screws and slots that allow adjustment to the total advance the distributor can have. At the wide open setting, it can have as much as 28 degrees of advance. If I were to set the initial at 12*, it would top out at 40*. If I closed the slot, the total advance is zero. If I set the initial to 12, the total would be 12 since there is no movement of the baseplate at that setting. THIS is where the Mallory tuning kit came into play. I wrote about this in September before I threw in the towel and pulled the heads. From 2004 until last year, the distributor advance was limited to approx 13-14 degrees. During this time I ran the timing at 17* initial and approx 30-31 total. This was by way of the adjustment of the baseplate. The Mallory tuning kit came with different width plastic keys/guages that were labled as to the effective advance that they would allow. The thinnest key/guage was 14. The kit also came with several pairs of springs. I took the heaviest springs in the kit and put them in both distributors. The result? They delayed the full advance about 400 rpms later than before. As was, the "curve" began immediately off idle and was all in by 1900-2000 rpms. The stiffer springs delayed the "all-in" until about 2400 rpms. on test drives, the car responded the same as before. I considered distributor tuning to be ineffective, so I moved on with another angle.
Consider my reasoning. I had over 190 psi cranking compression and 91 octane CA gas. I was around 11.0 to one with meager quench. I took the advice offered regarding cam swaps, colder plugs, researching vacuum leaks and distributor tuning. I installed an Air/Fuel guage and found that I was not running lean. All the while I swear I heard detonation no matter what I tried.