First, the reason that I was questioning this is the idea that higher octane fuel gives an engine more power. Not true. That would require a higher energy content and that isn't the case. Higher octane means more knock resistance, not more energy.

Second, the idea that more spark makes more power is also false. I dyno most of the engines I build and the amount of spark each engine needs depends on the entire package, not just the compression ratio. Having the engine run just below detonation is not the best for power! An example: during 1/4 mile testing of a low compression mid 14 second car I plugged in someone else's "perfect" advance curve (widely accepted) and lost 3/10ths. Slowed the curve back down and gained the time back. No pinging, so no octane issues, just too much timing too soon.

I've been building street and racing engines for well over thirty years and have used the same equipment that I'm sure Shornack has. The "test" is running it on their distributor machine to make sure that it is close to what has worked in the past for other engines. Not tested in your engine, but a best guess. I admire your faith in their best guess at the advance curve but that's what it is. Until the engine is run under actual conditions and tested, that's all an advance curve is, a best guess. The curve is a starting point, not the end point.

During actual testing on the dyno, the engine tells you what it wants by making more or less power, and when you curve the distributor accordingly, then you will have the "perfect" curve. Testing at the track is much less accurate and will give a more general trend for the amount of timing and the proper curve. Testing by most people on the street involves making sure that the engine isn't going into detonation and if it is, adjusting the curve to suit the actual conditions. But still better than a guess.

A quick advance curve is not the answer for every engine, and Doug has provided the info needed to demonstrate that and to fine tune his. With an adjustable timing light and a tach, he can set his mechanical advance curve in the car through testing better than Shornack can guess at what the engine might want. Obviously. And ignoring what the engine is saying by "fixing" it with more octane is not the right way. Fix the curve.

Too much timing and excess octane to cover for that will not make more power.

Doug, once you have the curve fixed, you can test for the proper amount of timing and then decide whether you need more octane or not.

Yes, Jim, I read it. I've also done a lot of other reading and testing.