You are leading & jetting for the worst (knock prone) cylinder: smallest chamber with the sharpest exposed edges, least water circ to the plug and exhaust port, narrowest exhaust port.
Anything you do is only a test to be verified in the field. 50 is safe, 2,800 sounds safe until you know better, but RPM will finally depend on converter lock-up, stall speed, axle ratio. A really big engine turning 2,000 at 70 MPH might like all spark in already.

I've posted A134 here.
https://www.tapatalk.com/groups/racingfu...s40.html#p16466

Polyyspheric, thank you for the information...60* light load is interesting!

That gives me something to think about went doing tuning the ECU.

Thank you, again!

Mattax,

Exactly what I was looking for! The information on Page 4 & 5 is perfect for me to set up the advance curves, and how to simulate a vacuum advance in the ECU Spark tables, including what the modifier tables do in relation to the MAP vs RPM tables.

Thank you very much!

Mark

If you have data recording you're looking for the highest vacuum at any constant RPM. Even if plus/minus small vacuum spark increments may not feel different, higher constant manifold vacuum reading always indicates lower load, coolant temperature, better mileage etc.

on my 330hp 383, I backed my light cruise timing down to around 52* I think. I had more to start, but watching the pyrometer and listening to it I dialed it back a bit.

Great! Thought it might be

Depending on what you've done to the engine, you can experiment with more initial or more along the whole curve, etc. I've found it useful to think about tuning from the combustion viewpoint. Basically trying to keep in mind the goal is combustion to develop such that maximum pressure is through the most favorable crank angles in terms of leverage. And if we know an engine has been built in a way that produces slower combustion in certain conditions, add more lead there.

For example an engine with more overlap at idle will exhaust dilution and less compression so will probably be a slower burn at idle. Same engine when fully warmed up may be more efficient in the mid to top range under load and develp pressure more quickly then.

To add to Polyspheric's observation. The higher vacuum should be for a given throttle open along with steady rpm. To some degree that will go hand in hand. That is, a small throttle opening at a given rpm should show as higher vacuum. I'm not sure how you evaluate the data when you are controlling using MAP as one of the inputs.