dbssr1212

Well I just swapped in a bp 12a into my new fb and we couldn't get it to start because it sounded as if it wanted to but it just couldn't
well my boss tried to get at the carb and pull the throttle a couple of times to get it started, then when we got it started and runnin he said ok cut it off


well
took the key out still running and revving nonstop all the way to about 8
couldn't get the spark plugs out and one of the direct fire ignition coilpacks started a little flame
couldn't stop it and the headers were bright red and well it set off the shops smoke alarm

we had to pinch the fuel line to get it to stop


what the hell happened and how do we fix it???

DivinDriver

iTrader: (15)

Fastest way to stop a motor under these conditions is to block the air intake if you can safely do so, using something much too big to fit down the carb bore.

LAST thing you'd want to do is try to take spark plugs out of a running motor (!?!) Even pulling the high-voltage lines is risky, because they will arc to ground and can start a fire or wreck electronics. Or bite you.

As to what happened, sounds like the throttle jammed WOT when he pulled on the cable, or maybe the secondary linkage failed open.

Failure to shut down by cutting ignition means you probably have an ignition switch or wiring fault.

trochoid

iTrader: (6)

Make sure your alternator has a good ground to the block. Not being grounded can cause the engine to run on.

dbssr1212

well i was in the car and my boss is a body man
the mechanic was on the phone lmao in boston and were in southcarolina (he's doing cars for another movie)

so the bodyman tried to take out the spark plug wires
shocked the hell outta him

but yea we got it runnin
the alternator is what we thinks wrong
probably the ground
i might have to make another ground when i get back there (im in tennessee for a family thing)
but could it just be that i tied the alternator ground into the same as the gauges on the block???

trochoid

iTrader: (6)

The alt grounds to the block through it's body. I discovered that one when I powdercoated the one in my FC. PC makes a good insulator. Once I ground the PC off of one of the mounting ears, the problem went away.

dbssr1212

yea im wondering if that could be the main problem

i'm running the second gen direct fire ignition
if anyone knows bad83s bp12a he had in the sa
I bought his SA and now the 12abp is in my fb but when we wired it up we got rid of a few things and had a little troube with the wiring since 84 and 80 has the different harness but well i was supposed to get an msd set up
but my boss couldn't find the box

='( the box was free it was actually from the movie Talledaga Knights he has a shitload still from the cars they built so i was gonna get that for free and an msd blaster coil 2 for free so all i had to get was 1 more msd coil pack and i'd be set but now i have to use the old direct fire instead becasue we couldn't find the box but when he gets back in december msd maybe =]]]

trochoid

iTrader: (6)

With no emmisisions it only take 3, maybe 4 wires to get a 12A running. If you have the wiring diagrams for both years, wiring up either isn't that hard. Keep in mind the 80 has J-105 injectors and different coils. You will need an upgraded ignition for the BP. Something I still need to do.

dbssr1212

we have a second gen direct fire ignition on it
but im wondering if its not the alternator where the blocks been painted or w/e if thats not acting as an insulator and killing the good ground

cmanns

^Why not scratch away the paint anyways?

dbssr1212

because do you go and scratch off paint after you just paint a car?

cmanns

Well I can't picture where the ground is exactly for his case but aslong as it's not out side the engine bay which I highly doubt any smart person would put it outside... what would the issue be?

I'd just take alil wire brush spin it around where the ground bolts down and whalla

trochoid

iTrader: (6)

The ears on the alt where the long bolt goes through to mount it to the block is where it grounds. When I had trouble with mine, I simply sanded the paint off of the ears of the alt. I probably need to sand more since it seems the charging output voltage of the alt is lower than spec. I found it to be a very strange feeling turning off the ignition, removing the key and walking away, yet the engine was still running.