Another 1405 vs 1406 thread

73Charger318 said
This is very interesting indeed. I see so many people saying how wonderful the car runs by simply changing the jets and rods on the 1406 to a stock 1405 set up. ...
Are they just getting lucky?

Some yes, some no.
Luck: There seems to be a bit of luck of the draw with which internal variations may come on any particular carb.
Not Luck: If you have a very similar vehicle, ie engine, ignition, gearing, weight etc, then copying a good recipe will provide similar results. Saves a lot of time and effort and generally gets you pretty darn close.

I think it seems smarter to try step #23 on the 1406 manual to richen things up a little then to stick a 1428 jet in a 1406 and have the set up found nowhere on the chart in the manual, let alone in the proper shaded area.

Depends on each persons ability to tune. If the chart is not getting the expected results, investigation or a different approach is needed. If the chart is working as expected, then use it.

Does deleting an existing EGR change how you should tune at all?

If you have a vehicle working correctly with EGR and then simply disconnect it, the fueling and timing will likely be incorrect for the situations where exhaust gas is fed back into the cylinders. Off the top of my head, part throttle acceleration and steady cruising will be off and likely need some tuning. Cold engine and wide open throttle will be uneffected.