Spark Gap versus Timing Change?

[Red]

Something I'm curious about is the effect of spark gap on timing.

IIRC, The stock plugs on my car were gapped at 1.1mm, a size that is simply not available (or wasn't then) on any gap measuring wires. And the factory spec is that same 1.1mm in the manuals.

But, OEM replacement plugs have always shipped at 1.4mm giving me a short (very short<G&gt feeling of guilt as I regap the new plugs that all say "WARNING: DO NOT CHANGE GAP" on the box. Yeah, well, too bad.

But I know that when the gap changes from 1.1mm to 1.4mm, it will take slightly longer for a spark to build and jump the gap, and in theory that should efectively change the spark timing the same way that changing it on the distributor would.

My question is, does anyone know for certain what this difference is? How many degrees of timing (or parts of one degree?) does the timing shift when the gap goes from 1.1mm to 1.4mm ?

And could this be part of the reason why the 86/87 models were rated for better guel economy?