Ignition advance

[ecoangel]

1.6HF igntion advance curves: Both 1600HF and v1016 seem to have same Magneti Marelli advance curves in the Lancia Manuals. My car was tuned on a rolling road by a chap who owned a Fanalone in the early 1970s. The curve is as per attached pdf. Seems a little different to standard - any ideas? Best Rgds

[1,6 HF]

Any advance curve controlled by centrifugal weights and springs will necessarily be a compromise or an approximation. So my tendency would be to treat the factory advance curve as a useful starting point, but I wouldn't allow the "official" curve to overrule the results of rolling road tuning.

That said, not having access to a rolling road, I've had my distributor calibrated precisely to the factory curve. In other words, having no evidence to the contrary, I'm starting with a "useful starting point."

[ncundy]

What ignition system are you running and what is the static advance?

When you overlay the standard curve + static advance (8 deg) they don't look that different to me from about 2000 rpm onwards. Does your curve include static advance?

Not sure what is going on below that, but my guess is it's running about 6 deg static but with a more aggressive curve in the first stage - presumably because of the cam profile? What is your idle speed set at?

[1,6 HF]

If you look at his original print-out, is does indeed appear that eco's dist is set at just under 6 static (I run mine about 5), and I'd agree that it approximates the curve you'd expect given that. I suspect that the dip in the curve at lower revs is a matter of the weights/springs not behaving in purely linear manner--not particularly surprising.

[ncundy]

Or the first bob weight has been modified to come in later and more aggressively by making it heavier and changing the spring and stop point.

Did the tuner tell you what he did, as it seems the only significant difference is the first stage, although the second stage is a consistent 1 deg ahead of the standard.

[1,6 HF]

Neil, that's certainly a possible explanation. But if the tuner actually changed the first-stage weight or spring, I wonder why he'd want to make the advance so non-linear, and why he'd want so abrupt a transition between 1500 and 2500.

So I could well be selling eco's tuner short, but I'd be surprised if the weights and springs were purposely modified to achieve that curve. Perhaps I'm missing something obvious about the performance advantage of that curve.

[ecoangel]

Not sure about static timing but he said max was 28 deg adv.

Power curve here:

[ecoangel]

Ignition system is Standard MM Distributor, points plus MSD 6AL and MSD Blaster SS coil with Magnecor competition leads, NGK race plugs.