A modern fast burn closed chamber head requiring 36 degrees would tell me that the mixture is lean. That chamber looks very similar to the magnum head.
From The Magnum Manifesto:
"Flowology
Discussions of contemporary cylinder heads like the Magnum's are certain to include the term "high swirl." Swirl describes a flow characteristic of a combustible mixture charge as it is inducted through the cylinder head passage and into a combustion chamber that's expanding as the floor (the piston dome) falls away on the intake stroke.
As an element of turbulence, swirl refers to the spiral-like path the charge takes around the long axis of a chambered cylinder. In its third dimension, a flow component called "tumble" describes how a swirling mixture somersaults down into the cylinder. The theory is that the activity of the mixture promotes atomization of the fuel. Ideally, the movement of the air/fuel charge should match from cylinder to cylinder, and swirl should theoretically continue through the intake, compression, and power cycles. Where port, chamber, and dome contours impart the initial swirl on the intake stroke, the piston dome can be configured to maintain swirl on the compression and power strokes.
Used in the mid-'80s in Detroit powerplants to improve emissions and fuel economy, applied swirl science had previously surfaced in Michael May's mid-'70s work at Jaguar, as well as in Roger Penske's Larry Widmer-prepped NASCAR Fords of that same period. (For more information on swirl flowology, see "The Soft Head," July 1985.)
Those early applications demonstrated how well-managed tract turbulence accommodates extra-lean air/fuel mixtures, and how swirl can improve combustion quality to reduce a mixture's sensitivity to detonation. The more mixture activity that occurs, the better the fuel remains in suspension and the better the mixture burns. The faster a fuel burns, the less ignition timing is required to produce equal power. And because wet fuel doesn't burn, or burns unevenly at best, swirl helps create and maintain a fully atomized air/fuel mixture.
Uniform fuel dispersion throughout the charge permits an engine to run leaner mixtures, while simultaneously reducing peak cylinder pressures and taming sharp pressure spikes. This means that a high-swirl engine can run more static compression with less chance of detonation under load"
Chrysler 360/380 A-Series Crate Engine - Hot Rod Magazine
