You need to use a vacuum gauge with the A/F gauge when you road test and keep an eye on, compare, the A/F to the vacuum level as you crowd the throttle in part-throttle acceleration when the PV is not open. You want the A/F to be as lean as it will run well at a cruise and any mid-pedal acceleration when the vacuum is above the PV opening point. As you crowd the throttle harder the engine will tolerate leaner A/F, and that may be as lean as 16.5 or even 17.5 on some engines which have good or better than average vaporization and A/F distribution characteristics. Use as lean a main jet as will accelerate at part-throttle without balking. In fact, the part-throttle torque and response usually improves with the leaner A/F up to the balking point.

Understand that the leaner it is, the more unburned Oxygen there is in the exhaust residual, so the successive combustion cycles have the advantage of hot Oxygen from previous cycles. It should come as no surprise that hot Oxygen improves combustion more than Carbon Monoxide. Also, leaner than 14.7/1 (stoichiometric) the temperatures drop off faster and more than an equal percentage on the rich side. In other words, from 15/1, 17/1 is cooler than 13/1, however the lean A/F burns slower and so needs more timing, AKA vacuum advance. The highest temperatures occur near and slightly rich of 14.7/1.

You are hardly adding any 'vacuum' advance at all in your table.
I'm seeing just 0 to 2 degrees of vacuum advance.


Did you enter the initial and max. mechanical advance numbers based on your engine's dynosheet?
Do you have a copy of that to post here?

I presume the 609HP was made with a known timing advance curve and rpm.
That advance number could/should safely be put in the corresponding 100% kPa load field.

The porting afterwards would vary the numbers but a dynosheet should still provide a good lead to modify your ignition map in TunerStudio.

For Ref...cal table from Holley for 650HP 496"

Who's "reference table" is that?
Looks pretty stoneage to me.
Good luck starting an engine with 31° advance without idle/starting compensation.

I have just used bank fire, if not doing sequential.

I have just used bank fire, if not doing sequential.