lets revisit timing
For what its worth, here's little excercise I did using Dynomation 5 some time ago.
One green line is what the program calls the 'ideal' timing for a 340 with a cam that has roughly 223/230 duration .505 lift.
The other green line I got by trial and error reducing the timing every 500 rpm until the power was about 5% less.
Red lines are some real life timing curves that the real engine pinged mid rpm under some conditions.
Dynomation 5 (and its predescessors like Desktop dyno) is at least partially based on hundred if not thousands of dyno runs.
How much weight one should put on the timing results is certainly debatable. In general they follow the Chrysler curves. However I played around with the program enough to see if changing the rod-stroke ratios effected power and timing and wasn't seeing any difference. So that suggests to me that the program does not take into account all factors which would bear on valve events and ignition timing.
Just for fun* maybe later tonight I'll unlock the program and see what it spits out for 'idea'l timing of a stock early 340.
*Obviously what I consider fun or interesting may not be the same as some others.
For what its worth, here's little excercise I did using Dynomation 5 some time ago.
One green line is what the program calls the 'ideal' timing for a 340 with a cam that has roughly 223/230 duration .505 lift.
The other green line I got by trial and error reducing the timing every 500 rpm until the power was about 5% less.
Red lines are some real life timing curves that the real engine pinged mid rpm under some conditions.
Dynomation 5 (and its predescessors like Desktop dyno) is at least partially based on hundred if not thousands of dyno runs.
How much weight one should put on the timing results is certainly debatable. In general they follow the Chrysler curves. However I played around with the program enough to see if changing the rod-stroke ratios effected power and timing and wasn't seeing any difference. So that suggests to me that the program does not take into account all factors which would bear on valve events and ignition timing.
Just for fun* maybe later tonight I'll unlock the program and see what it spits out for 'idea'l timing of a stock early 340.
*Obviously what I consider fun or interesting may not be the same as some others.
