Continuing ignition timing debate from the 416 thread.

Newbomb Turk said
Yeah, you can catch a hot plug real quick loading the engine steady state.

You certainly need to be aware of it and watch the numbers.

I know guys who would never steady state an engine. They think it’s hard on them but if you think about a boat they are constantly loaded.

You can also see how the A/F ratio changes under steady state testing.

I’m assuming that is another reason why sweeping tests let you run more timing than steady state because the a/f ratio is much different.

Plus, I’m not sure on a sweep you have enough cycles for the change in timing to take effect.

Tuning a boat motor might be done better steady state since that is how it will be used mostly. If there is a change in a/f ratio after some period of time at steady state then you would see it. And sweep testing might be better for motors that sweep through the rpm range.

Newbomb Turk said
Ok, I had to find the Superflow book and my notebook.

Going off my memory I got it wrong. Superflow says 100 cycles and the other people I talk to said it’s 250 if not 300 cycles to affect a change.

SuperFlow is talking about how fuel behaves while testing. But the time is the same. And it affects ignition timing the same.

Cycles is rpm. It takes 100 cycles to affect a change. Again, that’s what SuperFlow says. I believe it to be at a minimum 250 cycles.

It’s the exact same with timing. When you are moving so fast, even at 300 rpm/second it’s too fast so the engine thinks it wants more timing than it does.View attachment 1716472562 View attachment 1716472563 View attachment 1716472566

I finally had time to read this and it's good information. Thank you for taking time to take pictures and share it. As you said there is no mention of timing in this paper. It also is a strong argument for sweep testing if that is how the engine is going to be used. And steady state testing for motors that will be used in a steady state.