[mylesdw]

Cobra 29:
49 degrees sounds a lot but theory suggests it is OK-

If we know that 12 degrees initial is Ok and if we assume a tickover of 600 rpm then that tells us that it is OK to light the mixture 3.33 milliseconds before tdc under no load conditions.

At 49 degrees advance and 2500 rpm we are firing 3.26 milliseconds btdc, in other words slightly retarded in real terms.

In a pure overrun condition (foot off, no load) this would be fine. How quickly the vacuum advance is removed as you apply load is the more important factor.