Well, I went out to run the valves and torque the heads on my recently-assembled 383... and found my little truck had been playing "car-b-que".

I went and snapped some pics w/ my daughter's camera, but she's got the cable; won't be able to post pics until the weekend.

Let me give a rundown of what had happened on the last trip home a couple days ago, and what I saw today - see if anybody can do the forensics on this. I'd like to get the cause figured out so I don't have it happen again!

I went over to a friend's house, about a fifteen minute drive. The cooling fan switch (brand new part ) had failed, but there were only three stop signs; shouldn't heat up too bad - get to keep moving. Got there w/o incident. Had the hood sides up showing off the new motor.

No signs of anything hot (other than the weather; it was about 95 out).

Took the old girl home; seemed like no problem. When I passed a car pulling into the driveway, I thought I smelled something hot, but just for a moment.

Today, I found that the coil wire (wire set had about 1 week run time on last motor in the truck, five years ago), all four pass side wires, the distributor cap, and the cap end of all four drivers side wires were burnt. To a crisp. The insulation turned to powder in my hands. There's a hole the size of a pencil eraser burned thru the cap.

The wire boot on the coil tower appears to have turned to very hard plastic and fused to it. The coil WAS an MSD Blaster 2. Stock ign. module and ballast.

There was soot all over the hood and across the firewall.

The heater hoses which ran over the pass side valve cover were burnt in half. One of 'em is missing about a foot of hose.

The two small wires going to the alternator fields have some heat damage to the insulation, but only where the plug wires were close. Not at the terminals where they plug into the alternator.

The old girl was running about 195-200 coolant temps, but it was in the mid 90s out; I figured that wasn't too bad. There was no steam or smoke coming out of the truck when I shut it off. And it didn't miss a beat; didn't misfire, buck, etc. Ran like a champ.

I thought I might have had a fuel leak (my pressure regulator is on the side of the tunnel ram, right over the pass side where everything burned), but I couldn't find any signs of leakage when I washed the area off.

Anyone have ideas about the cause? I've seen the ends of a wire burn up from a bad connection - not half the d**n set. Did the MSD just get too zippy for the secondary ignition? Do I just need to put it back together with some hickory chips and a pork shoulder?

Hoping someone can shed some light on this; I'm pretty lucky I didn't lose the whole pickup!

Thanks,

Bill

ya, my guess is you had a fuel leak and it went WHOOOSH from the engine heat.

youre lucky it went it out

Fuel leak and fire.

I'd thought it was fuel lines, too. But had to rule it out after inspection.

All hard line there; no signs of leakage.

No signs of fire on fuel lines. If they'd been spraying on something six inches away that lit off, the lines would almost undoubtedly go up too.

And they were holding pressure when I cracked 'em to get at something behind the regulator today.

But, pretty sure this wasn't a fuel leak.

And it probably wasn't a wire laying on the header; the front two on the pass side went under the headers; the rear two went over the valve cover and between the tubes. And they didn't flop around a bunch or anything.

I'm wondering if it could have been foul play?

Don't want to be paranoid, but... I just don't see how this makes sense.

BTTT for more guesses.

-Bill

Awhile back a guy (on here) posted pics of his burnt rotor which iirc the rotor blade got bent from putting the cap on at an angle & the large gap made for some serious arcing but nothing close to the damage you have experienced (& it was all contained under the cap). I would not suspect foul play.

Yeah, I wouldn't want to think of someone burning poor Lulubelle. And probably not likely.

Looking under the cap, the terminals were colored blue-ish. But there was no bad pitting; nothing like you'd see if it was hot enough to start something on fire.

I think the rotor was phased pretty well; the little marks I could find on the terminals were in the middle.

I'd wondered if the coil wire started it, and then caught other wires.

I've seen the terminals burn off the ends of the wire if there was a problem, but never just flat go up in smoke.

I've put in a PM to SunroofGTX; first, I need a wire set (duh), and second, maybe he's run across something like this before.

-Bill

there is no way an ignition system could melt down like that without fire. a spark plug wire is so heavily insulated that it nwould take a HECK of a lot of power to melt like that. the ignition feed would melt and dissolve WAY before the spark plug wires melted. the fuseable link would be gone and the car would stop.

you leaked fuel. check your carb. probably spit gas out the fuel vent. Holleys?

very random thought....

While getting my FILs chivy running last weekend, we managed to get it to spray fuel out the throttle shaft a couple times (it's a bit worn)

One spray would be enough to do some damage, but otherwise keep everything else 'normal'; no fuel leaks, still have pressure, etc.

just for grins, I went out and powered up the fuel pump.

No leaks found.

I'm wondering if the carbs (AVSs) boiled some fuel out and filled under the hood w/ vapor.

Weird thing, I'm guessing the fire happened w/ the truck not running. There shouldn't be any power to the coil.

Something burned, which caught the plug wires on that side, the cap, and the heater hoses. I can't see how it could have been an electrical short causing the problem.

I'd REALLY like to figure this out so that it doesn't happen again - with worse results. But, I'm flummoxed.

I'm thinking of making an air box to go over the tops of the carbs and piping fresh air to 'em from in front of the radiator. If this IS a fuel vapor thing, then that may be a cure for that issue, too.



Thanks to all who took time to post. If this were a dead obvious thing, or easy... even I would have caught it.

Hopefully my kid will bring the cable so I can post pics Sat.

-Bill

i drove my car 2 weeks ago. It started fine and i drove to a friends shop and parked it for an hour so so. time to go, i cranked it up and it started, ran real rough and died. crank crank crank crank. no start. foot to the floor crank crank c4rank BRUUUUMMMM!!! stumble stumble cleaning up running ok.

I go and open the hood cause i knew what happened- dont know WHY- but know what. Took off the air cleaner and sho nuff, gass on the top of the carb near the fuel bowl vent tube (the vertical vent tube on holleys). junk must have stuck in the needle and flooded it out, filled the bowl, dumped fuel on the top of the carb and air cleaner then fixed itself.

If that had happened just before I shut it off, and enough gas got on the manifold, the engine heat could have vaporized the gas making it more volatile and then WHOOF - fire.

I had that happen on my truck before. blew me away as i never though gas would catch fire JUST FROM a hot engine. but it did and fast.

thats why my center carb fuel bowl vent coming out the side of the carb (not the one sticking straight up near the air bleeds) is capped and not open like lots people run on six packs. I wont ever let fuel dump on a manifold again.

i am positive you had a fuel leak. like the other poster said, electrical melt downs are from excessive current- not voltage- and ignition systems cant do that kind of thing. if there was a short that drew that kind of current, you ignition feed wire would be TOAST all the way back to the ignition switch before a spark plug wire melted

The more I think about it, the more I think you guys are on the right track w/ fuel vapor.

It was hot as Hades out; perfect conditions.

The wires that burned weren't powered up - the car was off.

The stuff that could have been shorting doesn't appear to have been. This is backed up by the battery still having a charge two or three days later.

Well, I've ordered a new set of Firecore wires from Rick. Now maybe I'll just have to buy a barbeque to cook the pork shoulder and keep the truck as a truck.

Hopefully, I'll have the following results...



-Bill

Quote:

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I thought I might have had a fuel leak (my pressure regulator is on the side of the tunnel ram, right over the pass side where everything burned), but I couldn't find any signs of leakage when I washed the area off.

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Check the diaphram in the regulator. There should be a vent in the body of the regulator where fuel will pour out if diaphram is compromised.

What carb are you using?

Do you have an idle stop solenoid on the carb?

It's time for a pic

Hi all, and thanks for throwing in your !

Keep it up, and I'll have enough to buy lunch (at least for myself).

I think it gots to be fuel vapor.

Todd, I ran the pump yesterday and watched for leaks (because I figured maybe I shouldn't dismiss it out-of-hand so quickly) - none seen at the carbs, lines, or reg. Can't run the engine to see if it spits out the throttle shafts (was running at low throttle settings for the last 2 miles home; wouldn't it suck air instead of spit fuel?). Won't know that until the wires come. Didn't see anything out of the regulator (is up in that same area)

Yeah, I was REAL lucky to not lose the truck! I think I have to thank the burned heater hoses for spraying water when they went.

As far as the source of ignition goes... if it'd been set off by spark inside the cap, I'd expect to have seen soot in there. Probably. But, you never know...

'69', whether it was a hot header tube or a spark from inside the the cap or from the alternator (also nearby), we'll probably never know.

Stumpy and Harms, I'm using AVS carbs, 275HP/327 Chev carbs (seem to work okay; came bundled w/ the manifold); no dashpots, idle solenoids, or the like.

Yeah Robert, still waiting for the kid to come so I could post up pics from before I cleaned up. I'll throw up some pics from after I pulled the burned junk out that I sent to Rick at Firecore.

Disclaimer: they're from my cell, uploaded to snapfish - low res stuff! This one shows where I'm thinking of mounting the coil (off the motor; no more vibration) with the tower pointing AWAY from the top of the radiator (so if it gets sprayed, it won't douse the business end of the coil).

One toasted cap

The the 2 rear wires had been run over the valve cover; not really close to the header tubes