Just got my 72 Chevelle going. Ran fine day 1 then started just turning off like the key turned the car off at low RPM at high RPM it would cut off breifly about 1 sec then get back going again. One time I actually seen the Mallory 685 blank out and stall while the hood was open. Then I went in car and started it right up again.
Mallory Coil
Mallory 9000 Unilite Dist with 605 module
Mallory 685 box
I have ruled out the 605 module as it runs real good with no issues with box bypassed
Has anyone else had similar problems/experiences with these boxes ?
What really sucks this is a BN box but was purchased several years ago sitting new in the box.

I'm having the exact same problem with my newly rebuilt chev 350. I have replaced the ignition module in the HEI with a mallory stock replacement, I have installed a mallory coil, I changed out the coil in the magnetic trigger part of the HEI but not with a new one, and I still have the same problem.

At exactly 500 rpm, it shuts off like I turned off the switch. I'm glad I'm not alone and I want you to know you aren't the only one either.

I have contacted Mallory threw their website and they are of no help whatsoever.

They claimed that aftermarket ignition modules can cause this problem due to the lack of a "dwell circuit". When I first installed the 685, I had that problem with my accel module. I changed back to a stock module and it ran fine. Then after my recent rebuild the problem came back.

I haven't a clue what else to do to make this thing idle. It runs fine with the 685 in play as long as it stays over 500 rpm.

I really hope we find the solution to this problem.

Dave