I have mentioned this before on the touring forum, but as a V-8 builder, the number one reason for a glowing primary pipe on a car is retarded timing, NOT lean mixture

Before you guys launch, I know the Harley is lean as hell, not arguing that, BUT, consider this too

A lean mixture can make for some hotter EGTs but generally the real exhaust coating melter, glowing red pipe, etc is due to late ignition timing.

(Those with a non EFI car with headers, try it..... crank the timing back to 4 BTDC and let it idle at night, they'll glow RED, dont do it if you run ceramic coating, it'll melt right off)

As a guy who has had to make lots of street motors pass MA and then NV emissions, the best way to get the exhaust cleaned up is ALSO retard the timing, see the connection here? Harley and EPA, running hot, seems to match up but I dont know the curve info for the stockers

Thats why when we build hotrods we always have to recurve the distributor, because the timing curve is built for emissions as much as the fuel curve, maybe even more so

Does anyone know how the timing curve is set up on these late models? Especially initial timing.

The last alum headed 460 Ford I did ran like a monster at 15 initial, 36 total all in my 2700. To get it to pass (as with scores of others), all we needed to to do was retard it to 6 BTDC and slow the rate down to have total timing in by 3300 RPM, that passed the idle and dyno emissions with no other change. It was a pig until I got the timing curve dialed back in, but I didnt lean it out at all, despite it failing miserably as originally tuned. Matter of fact, leaning a motor can often increase emissions due to a incomplete burn.

I am wondering if we are fighting a known lean condition, when idle and low rpm exhaust heat may be more an issue of timing

If anyone knows the factory timing curve in some form or another, I can get pretty far from there

Thanks