1971 f100 electrical issues on a fun motor swap

[dcaudet]

hey folks, i've come to a dead end on my electrical hunt and need some guidance.

what i'm working with is a 1971 f100 that originally had a 390/4 speed combo.

last week i swapped in a twin turbo 302/c6 auto out of a 1995 mustang.

now this is where it gets fun, after the motor was roughed in we fired it up (one person in the cab, one on the carb as the throttle linkage was not hooked up yet).

motor ran perfectly, shut the truck off and trailered it home from the shop.

got home, hooked up driveshaft, heater core hoses, trans shifter, boost gauge, correct starter for the '95 302...
on test fitting one of the heater core hose fittings, i accidentally grounded out the alternator wires to the header (battery was still hooked up, first mistake, i know, lesson learned)

sparks flew up to the hood for 5-10 seconds until something went pop and power was gone.

i figured i popped the battery or the starter solenoid. had the battery tested, still good. replaced the solenoid, replaced the relay, rewired the starter.

now, where i am really getting confused. i have ZERO power in the cab unless i am jumping from the positive battery terminal to either small studs on the solenoid.

when jumping i can get lights and such to work in the cab but not the ignition.

since i have replaced most everything could my ignition have fried? i feel like the fusible links(solenoid/relay) would have protected the ignition.

what's everyone's thoughts on this? what did i miss? electrical is never fun and i've been chasing this for two days now.

thanks

[68RGR]

Check the yellow wire that feeds power directly to the ignition switch via the black/yellow stripe wire that connects to the solenoid terminal. If it has 12 volts on it, then the switch is suspect.

The fact that you get no power until you jump from the battery to the solenoid might mean your positive battery cable was damaged during the fireworks.

Your best bet is to use a test light or voltmeter to follow the wiring from the battery to solenoid to the ignition switch. Unless the switch is bad, you have some issue that has opened the circuit between the battery and the ignition switch. The yellow wire connects to the black/yellow striped wire under the dash in the vicinity of the ignition switch and fuse block. It's sort of a big black blob if I recall correctly.

[dcaudet]

i think its starting to look like its the voltage regulator. i'm going to pick up a new one tomorrow and at least check that off the list.

the solenoid is good, the relay is good. everything runs back to the cab. but where the link seems to be broken (fingers crossed) is at the volt reg. the yellow to its clip is good. then the yellow out to the cab is good.