Ah man! thats lucky!
Reminds me of the time when i was younger that i used the trunk release wire in my car to wire my amp and sub in the trunk. I find trunk releases from the cabin to be insecure anyways so i thought.. why not!
So what happened? i was driving along, rocking that bass, and suddenly the cabin starts to fill with smoke and my girlfriend at the time starts screaming! we pull over and both get the F out of that car as fast as possible! i pull out the battery connection (just ripped it right off the terminal i was so amped up!), but by that time the smoke was starting to clear and there was no visible fire.
Problem was that a cheap chinese fuse i bought at the dollar store melted in the fuseblock and the metal parts of the fuse contacted heating up the wire and burning the coating off the wire all the way along.
luckily, that was unbelievably the only wire in the harness that was damaged! i removed teh melted mess of a fuse and started the car up and drove it home.
Then i ran 10 gauge to the trunk a few weeks later and it was all good after that.
I was cleaning burned wire goo from various spots on the chassis and under the dash for years afterwards, but it could have been FAR worse!
I always remember that mythbusters episode where they try and try again to light liquid fuel on fire and simply cant do it. their conclusion was it has to be vapourized to ignite by heat, or static, or shot from a gun (kinetic), or whatever. But i guess spraying a bunch of fuel all over the engine compartment with a (backfiring?) carb and literal flames was enough to do it in your case! im sure there was plenty of aresolized vapour in your engine bay at the time as well.
man so lucky… eric does the learning so we don’t have to!