I have been here.
What may help is to replace the "Molar" distributor. Teeth do a terrible job of distributing spark.
Kidding. My Iphone changes MOPAR to Molar.
Back on topic: The MP distributor has a REAL fast curve and light weights. It provides about 28 degrees of advance in a very short time. The amount of advance needs to be limited and the rate of advance needs to be slowed down. Mallory ignition made these distributors for Mopar engines. They also sell a kit to tune them. You need to replace the advance springs with stiffer ones that slow down the rate of advance. Then, the kit includes plastic "feeler" guages to set the total amount of advance the distributor will give. It is not a difficult job.
Example:
If your distributor is stock from the box, you install it and set the static timing to say...10 degrees BTDC, the total timing will end up at 38 degrees before 2300 rpms. Any engine with a mild to moderate cam will need 15 degrees or more initial timing. Setting to 15 degrees to get a good idle puts you at 43 degrees total. This is WAY too much! Most Big Block Mopars run best between 32 to 36 degrees. This means that you have to shorten & reduce the total amount of advance the distributor delivers. I have this distributor in my 440/493. I have mine set to 19 degrees initial with 33 total. That is a 14 degree curve. Again, the stock setting allows 28 degrees of advance! I also replaced the springs with stiffer ones so that the advance comes in a little later. Who needs all the advance in by 2300 rpms? If one has a 3000 stall converter or higher, what sense does it make to have all the advance in 1000 rpms earlier?
I has trouble with detonation for awhile and asked for help here and on other sites. Some people were very helpful but very few were able to clearly explain what to do. So often there is a disconnect between what a person means to say and what they actually say. They feel that they are helping but their message comes out wrong or details get left out.
My setup was different than yours in a few areas but still very similar. I have a 440 block, 4.15 stroke crank. Pistons sat .012 below deck with Edelbrock heads. They had been resurfaced a few times so they showed less than their advertised 84 cc chambers. Mine were closer to 82 ccs. I have 2" TTI headers, an Edelbrock Performer RPM intake, 850 Demon and at first, the famous MP 292/509 cam. I later tried an aggressive Lunati solid lifter 316/326. I now have the MP 284/528 solid.
My calculated compression ratio was at 10.99. The engine made great power but would ping/knock at full throttle. I ran 110 octane gas one time and it did not knock at all. I didn't want to deal with race gas and the limited availability so I looked for another way out. The distributor mods helped some but it was not enough. I ended up installing thicker head gaskets to lower the compression. SOME guys online swore that it would not help, that it could run worse....Not true in my case. In the 2 years I have had this setup, the only knock/ping I have had was on an old tank of gas in the summer and it was barely noticeable. On the next tank of gas, there was no knock.
