need help hunting a shorting noise on sbc WITH video.

Hey guys,

While the video is uploading i thought i would start this post quick.

I have a 1969 ish 307 cid sbc in my ford that i have driven more or less trouble free for 3000 miles. Driving to KC about 50 miles out i started having issues and when we got home PorknBeaner helped me find that it was a distributor issue.

It has your standard for 79 factory hei and it had lost the spring that holds the rubber nub under the coil so how it was even running is beyond us as when we pulledthe cap off the little button was just sitting there and the spring no where to be found.

A quick trip to the store and back and we installed a new coil, rubber washer, spring and button and put it back together.

everything seemed just dandy but when we pulled it out of the garage we did notice a passenger side wire shorting when it touched the valve cover.

so i ordered myself some msd pre cut over the valve cover street fire wires from speedway.

They showed up and i put them on and i get this crackling!

you can hear it pretty accurately in the video, speedways tech has no idea, msd's tech said put more grease on the boots which i did to no avail and all the suggestions by friends have given me not luck.

so before i say screw it and have speedway send me another set as i find it hard to believe id have 8 faulty wires i thought id have you guys give it a listen.

I have today and tomorrow off so i need to get it sorted out or the plug wires sent back by tomorrow night so any thoughts or ideas would be appreciated, suggest the winning answer and ill buy you a beer at the hamb drags haha.

ok im going to load the video the youtube now and then ill come back and insert the video into this post

edit: looks like 26 minutes until the video is loaded and live.

 

<iframe width="420" height="315" src="//www.youtube.com/embed/5Dg2RXd9-SY" frameborder="0" allowfullscreen></iframe>

ok in 26 minutes that embedded video should work? 3:57 central time right now

 

A spray bottle with water in it will help find these kinds of problems. As the engine is running spray on the spark plug boots, distributor cap, wires, etc.
Having a wire arcing from a plug wire AFTER wires are replaced, maybe x 2 is very rare.
It suggests that is very high resistance is in that wire.
Did this arcing start with cap removal, I'm guessing HEI big cap?
Did you replace the little ground strap under the coil? It's gotta be there.
Real common to forget or lose this.

 

and I'd be looking inside the distributor for the little coil spring. It may be bouncing around in there, shorting things out.

 

Smog_guy looks like 6 minutes till the video where you can see everything but ill go threw your questions real quick while we wait.

Did this arcing start with cap removal: no, we removed the cap and replaced the coil and other then running better nothing changed. no arcing noise until i switched wires

I'm guessing HEI big cap? : not really, its an a/c delco factory/small looking unit

Did you replace the little ground strap under the coil? I might need a photo to know for sure what your talking about but all the wires from the coil are new and attached.

Thanks for the help i just know its gotta be something stupid

 

Rocky, I can pull it apart and look but with it being brand new and installed all of 10 or 15 minutes of total running time do you think itd work itself lose that fast?

 

Pull it in the garage, shut the door and turn off the lights and you might see where the spark is happening.

Don't let it run too long with the door down......

-Abone.

 

VIDEO is up! when i played it on my camera it sounded like it caught the sound perfect hopefully youtube doesn't fuck it up.

Flamedabone, I did that the other night and saw nothing

 

oh, and sorry its a bad beard day today. lol

 

I would never even try that. Just not worth the risk.

But I do agree 100% that it will be easier to spot the problem in the dark.

 

Coil in cap? 1979 is big cap HEI.

 

Smog_guy, guess it'd be the big cap then. I've just seen alot of giant looking HEI's to have this one feel small i suppose.

 

you changed everything but the cap...change the cap

 

If it was just one plug wire, it would go tick.....tick.....tick.....tick.....


Your shit is going tickticktickticktick..... What makes that much noise is the coil shooting spark where it isn't s'posed to.

Take the cap and coil assembly off and look at it reeeeal close again. Make sure the little ground wire is doing what it is supposed to be doing and everything is installed exactly as it should be. Also check the rotor to see if it looks .....unusual.... While you are there, look inside the distributor body and module plate area for that missing spring..

Where's my beer??????

-Abone.

 

2racer , just seems odd that it was fine with the other wires. change the wires and now there's an issue you'd assume its something to do with the wires.

 

It doesn't sound like a short to me. Can hear it in the video, but it's running smooth. Just doesn't sound electrical.

 

Tim,
Maybe take a look at the wire terminal where the tach plugs on, it would be sending a pulse that would speed up with the engine speed. also this sounds a little off the wall even for me but make sure it is not a pole on your alternator shorting out on something. Long shot but I am a long shot myself.

 

Abone, I'll take it back apart tomorrow am and see what I have going on.

For shits and giggles anyone have a link to a photo that shows me what i should be seeing when i pull this apart?

From memory the coil just had two leads with tabs on the end that i put right back where the old ones were. a rubber washer, a spring, and the button.

and your beer is in Mo. come find me saturday

 

Porknbeaner, im going to pull it into the garage here in a couple minutes before i head out for the evening ill check those real quick.

feel free to swing by tomorrow if your just out causing a ruckus with that bike of yours

 

If you can't see the spark on the outside, that means it is doing something wrong on the inside. Mark your wires clearly, then reomve that whole cap/coil and rotor, put it on the bench where you can see it in the bright light.

Take it all apart and make SURE all the small stuff is installed correctly and the inside of the cap and rotor area looks OK.

If you don't find anything and the problem still exists, put a new cap and rotor on it. (a good one.)

I don't care what kind of beer you get me as long as it is cold and there is a bunch of it.

Good luck, -Abone.

 

I think it unlikely all your new wires are bad, you had a problem inside the cap, I would think it worth changing or at least a look inside...

 

you could pull plug wires while its running. If the sound gets louder because it doesn't have a plug to complete the circuit, you might be able to isolate what terminal/wire/plug is giving you trouble. Did you check for cracked spark plugs?

 

If that were a wire arcing... or several, the motor would not run that smooth. I am betting someting inside of the distributor is "amiss"...... pun intended.

Look under the rotor also.

 

X2 on the ground, some have a metal strap and some a wire. Should be 3 leads coming out of the cap.

 

Here's an exploded view

 

The coil hold-down screws will crack the cap and when you remove coil screws to look the crack disappears. The snapping can be that or the ground strap under the coil is missing.
Replacing cap is a great idea. I can see it's been around for awhile.
Don't overtighten new coil screws in new cap.
The snapping noise is too fast for one cylinder.
This is where I'd test drive. Ignition arcing like that HAS TO cause a driveability problem.
NO driveability problem--car runs fine on testdrive--noise is coming from something else like loose parts floating in dist cap?
Since you're going to remove cap, time to check centrifugal advance. With cap off grab rotor it should turn a bit in one direction and then snap back to original position. If rotor does not move or does not snap back quickly you should remove rotor and lubricate centrifugal mechanism under rotor. WD-40 or PB Blaster is fine.
Then reinstall rotor and work it back and forth until it moves the way it should.
Very common for people even experienced mechanics to get centrifugal weights stuck under rotor--not good.
If you find no weights and springs under rotor you have wrong distributor installed.

 

that exploded view is exactly what i wanted to see

I can see off to the right the ground strap that has a blade on one end and a eyelet on the other.

I remember putting the eyelet back in place to screw it all back together but now that i think about it i dont recall putting the blade from it into the slot!

maybe it was just leaning on it enough when we first started it for it to be a non issue and when the car rocked it broke the just barely there contact? that seems possible.

Ill be tearing into it in the morning.

oh, P&B i checked and the alt wires look fine and not doing anything and the wires that clip into the bottom of the cap look good as well.

I'll keep you guys posted and buy beer when i get to Joplin lol

 

I'm going to name every single thing possible so no matter what....free beer....

Good luck, see you friday. -Abone.

 

I'm seeing 2 plug wires, bundled against each other,...on the driver side; That can give you a cross-fire headache. They need to be seperated to avoid that problem.

4TTRUK

 

40fordguy I've run and seen them run like that a zillion times? I've never had an issue before.

They don't touch each other at the 'bundle' spots they are spaced away from each other a little bit.


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