Thoughts on tuning engines

[PGSigns]

"They say part throttle up to 50 (initial + vacuum + mechanical) on a stock motor." Not sure who they is but they are full of something from a bulls back side. What Rich is trying to tell you is that the piston design along with the shape of the combustion chamber have a lot to do with how much timing you can run. Some shapes are more tolerant to timing and some are not. You just can't say for a stock engine. If higher octane fuel is getting rid of the ping you can hear then there is to much timing in the engine at that rpm and throttle position. The higher octane burns slower and that is covering up part of the problem. There is still detonation going on that you can't hear. Every engine has its limits and its sweet spot for timing and fuel that makes it happy. You can not compare any two unless they are the same combination. Here is something to ponder. In the late 70's I was a boat mechanic. They way we would set the final timing in the 6 cylinder Mercruisers was to run the boat wide open down the creek and adjust the timing till we got max rpm out the engine and then backed it off a couple of degrees to keep it safe. Same exact engine in lots of different boats and they all had a little different timing. And they were all Chevy 250's.
Jimmy

Jimmy