I know the Mopar Performance book says to set the pick up coil to reluctor gap at .008 max.

How critical is this gap? What happens if you have the gap set much wider, say .040 or more?

Let's say it is an RB with a Mopar high performance electronic ignition.

it needs to be at that gap to work correctly , you need a brass feeler blade to do it .

Since the reluctor is self-powered, the gap has to be tite enough to close the circuit. If too wide, the box will not fire..

Just my $0.01..

W .040" gap it would not generate a signal (or not enough of one to trigger the ecu). I'd set it @ .006" at the tightest point keeping in mind that different reluctor vanes stick out (slightly) farther and vac adv will change the gaps as is is pivoting thru it's travel (got a Mityvac)

Thanks guys. I have it set.

I will tell you this, it will not run with a .065 gap.

It is simple
.008 is tight--the instructions give a range and you can be out there quite a bit more--The real problem is that they will not be equal--the Nopar Perf distributors are not built good enough for .008 all 8 points--Twirl that thing in a good light --look at the closest one--set it .008--to what ever .020 +- The key is that if it is too much gap the timing will "jump" around when you have a timing light on it and folks will tell you your timing chain is sloppy etc--BS! The gap is too big if it is jumping around-set it tight enough and it will be as steady as can be--That is the way to set the gap--- just enough that it does not jump around--

I made the mistake of incorrect air gap a few years ago....Quite a story. I was going to take the Charger to the dragstrip for the first time since I had installed the 493 eddy headed 727 4.10 setup. The car weighs about 3850, si I was expecting to be in the low 12 range. I figured that I'd gap the plugs to .045 and the distributor to .016 to achieve a bigger spark. I had 5 gallons of 100 octane fuel to mix with the 5-7 gallons of 91 already in the tank. It ran fine all the way to the track. I never took it past 1/2 throttle. I lined up at the tree, did a small spin to clear the tires, and brought up a load against the converter.... tree goes green and I ease into the throttle. Just when the secondaries started to open, it started to pop and sputter. I let out of it and eased into it again, same thing. This turd sputtered to a 14.68 and I was too embarrassed to take the timeslip.
At home I tightened up the gaps in both the distributor and the plugs. It ran like a raped ape once again. Its always better to run fast in an ugly car than to drag your ass in a shiny one.