I have done exactly what you wrote. I posted about it too. Before any distributor tuning was tried, I had initial set to 16 and it was limited to 30 degrees total, meaning the curve was only 14 degrees. It knocked with the 509 cam and it knocks with this one. Just for the sake of my own curiosity, I backed the timing off until it would NOT detonate at full throttle when running 91 octane. It knocked at 30-31. It knocked a few degrees less. I backed it off again and it did not knock, but was lazy feeling. At home i hooked a timing light to it and found that it was now down to 20 degrees TOTAL, so somewhere between 20 and 25-27 degrees TOTAL advance, it ran without detonation.
The plastic keys in the kit are numbered in even degrees starting with 14 and ending at 28. The distributor I have been using was already limited to 14 degrees by this same method. I read the instructions included in the Mallory tuning kit and used the stiffest springs that were included. This resulted in the advance starting about 350 rpms AFTER idle instead of immediately after. This was a step in the right direction, but the 14 degrees of timing was still all in by 2350 to 2400. This is why I mentioned that Maybe I need stiffer springs to S L O W the curve even more. The Mallory kit brown and orange springs are the the thickest and firmest in there. The weights are rather light though. I wonder if springs from another brand of distributor may be stiffer? I have several stock type distributors that may have springs that I can try.
I am surprised that you don't remember that I wrote about the work I did on the distributor and what effect it had. No, I am not necessarily anxious to pull the heads and spend another chunk of money, its just that so far my efforts have been met with minimal gains.
