Hopefully looking for someone that may have had the issue I've been having with my 86 camaro iroc z that can shed some light as I am stumped.
A little about the the car in question, originally a 305 tpi auto car , now its a 350 5.7 tpi, edelbrock headers and runners, bbk t/b, t56 6 speed manual swapped. Custom chip set up for current mods.

The car has a random issues where out of nowhere the car completely shuts off including all electrical power, windows, dome light, exterior lights etc. I turn the key and nothing happens as if battery is completely disconnected and after a few minutes all electrical power returns and car runs and drives as if nothing happens. There is no warning sign that the car is acting up and is going to shut off, doesn't stumble misfire or nothing acts like if you were to turn the ignition switch to off position and looses all electrical power to everything.
first time it happened in the middle of an intersection while at a light car shut off, couldn't turn on my hazards or anything, pushed it to the side of the road and waited for a tow truck, while waiting kept cycling key and nothing, I even hooked up a battery jumper directly on battery but nothing still everything was still completely dead. While waiting noticed the dome lights have finally come back on on their own and car restarted with no issues

 

Have you checked the condition of fusible link wires at the starter and starter lug for corrosion and being tight ?

 

Since the first incident of it happening i replaced the battery, the battery main cable to the starter, i added a junction block and new fusible links. The issue didn't come back for a good while over 1 year, I figured that was the issue, but until recently the same issue has returned . Car dies completely at idle, looses all power to all electrical for a few minutes then just restarts. Besides that car runs great, just sucks driving it not knowing when it will die and have to be pushed out of traffic 😣

 

fusible links have been replaced and battery is clean and has a good tight contact both power and ground.
as a test today I had the car idling I wanted to see if it would die the same way as it randomly does if I was to disconnect the negative or pos terminal directly at the battery and I found it does not die, it keeps running fine with the battery completely disconnected it does not replicate my issue. It keeps running and stays on with the alternator power

 

Anyone??

 

Check grounds on back of heads (doubt thats it)
Probably have to put it on a lift and wiggle test every power wire you can.

 

I will try that when i get a chance. Just seems strange to me that everything goes dark no power to anything, has always happened while on idle at a light so no real harsh vibrations to really move a wire loose and then just re start back to normal on its own

 

If everything goes dead all at once and it's not battery/alternator, the next place to start looking is at the fuse panel and the wire that feeds it power. Most of the cars circuits meet there, so that could be the nexus of your power loss.

I second TTOP350's "wiggle test"

 

that's a good suggestion checking the fuse panel I will try starting off doing the wiggle test there to see if I can duplicate the issue