Spark Plug Heat range

Maybe. It did with mine a little. What thermostat do you run? The number one biggest thing you can do to combat detonation is cool the engine temp down and cool down the incoming air/fuel charge. Of course cooling the engine temp down does the other. I had a 180 stock style thermostat in mine when I put the modified engine in and had some light detonation issues. I tried several things, including colder plugs and each made a small difference but the one thing that finally knocked it completely out was a 160 high flow thermostat. I have the factory temp gauge and before the swap, it would normally run a tic below half way to a tic over half way depending on outside temp. Once I put the 160 high flow in it, it just does make it to the first mark, no matter the temperature, and no more detonation, regardless of how hard I lug the engine. I highly recommend the thermostat. But it doesn't just need to be 160, it needs to be high flow as well. The trick is getting the coolant OUT of the engine as quickly as possible.

Hot 225 slant 6 with 175 PSI cranking pressure and 250 @.050 solid cam.