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Discussion Starter #1
This one is killing us. Need some help. My brother has a Vega with a 355 sbc supercharged and can't keep the wires from arcing out to the headers and other places.He is running a MSD -6BTM, a MSD Blaster HVC coil and a MSD Pro Billit dizzy. everything is new.
Just some notes, not sure if it means anything
When we first tried to fire up the engine it would not even pop until it was discovered that 2 wires were crossed. Corrected them and it fired right up as normal. Weird
-- Tried timing light on engine and it was reading like 140 degrees. We finally figure out it was picking up from another wire that was close to #1 and timing light pickup. Separated wires more and now it was at 32 degrees total.
- The engine throws off a ton of heat in a very short time and stays real hot for a while after you shut it off. He runs it with out a hood but it doesn't seem to matter. Except after one short ride he said it cooled down like a normal car. It has only done that once.
- He has tried several types of wires and now hase a new set of Moroso Blue Max with Moroso wire sleeves. The plugs are Autolite 3934. gapped around 22
- Just tried all grounds and added a new strap from the block to the frame and ran a direct ground from battery to MSD box and coil.
Sorry it's a long one but hoping someone has a clue or has run into this themselves.
 

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Try opening the gap, pretty tight even for a SC
 

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The spark will always go where the lowest resistance is.

I would look at the arcing at night and identify where the actual spots it's arcing from and mark the spot on the wire. Then I would remove the wire and examine it closely to see if there are any cuts or indication of burning. The damage may be hard to see, but if you bend the wire 90 degrees it will usually be apparent.

Those wires should be fine and should not arc if the wire is intact.

Have you simply tried another set of plugs?
 

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Discussion Starter #6
Thanks for the help.
We have tried MSD and Accel with this set of MSD being brand new.
We did open the gap to .35 with a new set of plugs with still some arcing.
Topfun99 thanks for the good info on checking the wires. This set has only minutes of run time on them.
Someone brought up about using antiseeze on the threads affecting the plug to head ground/contact. There is some but just a small dab when the plugs were first installed. It's a cast block with Dart heads. Maybe we can try a different coil. It seems like a ground issue though.
The car is not running much boost. The engine although is very healthy it's really only for show. Cruise nights and stuff. But can't really bet it to the show the way it is now.
 

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Opening the gap should make arcing / crossfire worse. Worst case is a cracked / broken plug or burned off electrode, or bad plug wire. This allows the coil voltage to rise, and "just like lightning" the spark will crossfire wherever it can get........through the rotor, across distributor contacts to adjacent cylinders, or through the wire insulation to wherever THAT can get.

I see those plugs are non resistor, so at least that is not a factor.

You might check into rotor phasing and make damn sure the coil wire is actually good. Since you changed plug wires, I assume you also have other coil wires.

Other than that make darn sure the connectors are seated on the plugs. Believe it or not, sometimes they are "up in the boots"
 

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Discussion Starter #8
I think you are onto it with the rotor phasing. We are going to look into that next just not tonight. It just seems to make sense with whats going on. I searched rotor phasing and the MSD video came right up. He also removed his cap and it had white stuff in there.
 

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Discussion Starter #9
Thanks everyone, I promise not to just end this thread without a conclusion on what we found to fix this. I have searched a lot of discussions out there and seems when they just about have it figured out the thread ends with out letting everyone know what fixed it and thanking the people that helped them get on the right track.
 

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Discussion Starter #10
While I was at the Yellow Bullet Nats my brother checked the rotor phasing of the distributor and it looked right. So that is out. He did say that the timing light is still picking up something else that is making it read timing at 105 degrees. We had that happen before. The inductive pick up is getting spark from another wire or something. We know timing is set at 32 total.
One thing He noticed was a lot of white stuff inside the distributor and under the cap.
Still open to anyone that has had this problem ( or problems ).
I will keep updating.
 

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There's also been "noise" around the www with guys having trigger problems caused by the energy of the MSD itself. In other words the spark energy falsely re-triggers the MSD. I would think this would cause misfire, but only depends on engine relative position. I don't know. The "white stuff" would be disturbing, to me.

Might be "the other way around." Might be you have some corrosion problem causing the cap to deteriorate. The "white stuff' is likely the remains of aluminum, and is likely conductive. You might try a brand new cap / rotor and immediately see if the problem is still there. The explanation in that case is that cap/ rotor deterioration from whatever cause, is allowing cross--fire to "unused" cylinders. Depending on what that cylinder is doing, it will might "see" a higher spark impedance than one under compression.
 

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I don't remember if anyone mentioned it yet but I would be suspect of the signal from the distributor to the MSD box.

If there is ANY WIRE with high voltage/amps near the signal wire after it leaves the distributor until it reaches the MSD box itself, it may trigger the MSD box. I believe this includes running near the alternator.

Make sure your signal wire(s) have twists in it, this helps prevent the wire from picking inductive charges from surrounding electrical wires and equipment.

On my ECU, the signal wires are embedded in a grounded wire harness to prevent this.

By the way, one other way to verify rotor phasing, is to look at the coloring/wear on the distributor rotor itself. On my car I can clean the rotor so it's bright and shiny. Then after running the car for a short time, I pull the rotor and examine the tip. I can tell where it's been doing the most "work" by looking to see if the leading/trailing edge is worn/colored more than the other side. On my car the leading edge typically wears more because of the advance timing (40 deg+) for all of the street driving. But it still wears along the front edge, not from the side edge.
 

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I don't remember if anyone mentioned it yet but I would be suspect of the signal from the distributor to the MSD box.



By the way, one other way to verify rotor phasing, is to look at the coloring/wear on the distributor rotor itself.
Yup
 

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Discussion Starter #14
The white appears to be basically from arc flash, so to speak. All these parts are brand new with not more than 200 miles on a car that never see's rain or moisture at all. I tried to post a picture but it's not allowed for me on YB.
It may be something simple that we are overlooking.
 

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Discussion Starter #15
Very interesting stuff guys, Thanks again.
He cut holes in the cap to look in at the rotor arcing to the cap.
I will have him check the signal wire. That can happen when you are trying to make it all look clean for show.
 

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Discussion Starter #16
If there is ANY WIRE with high voltage/amps near the signal wire after it leaves the distributor until it reaches the MSD box itself, it may trigger the MSD box. I believe this includes running near the alternator.

YES, The coil wire crosses the pick up wire.
Tried a new coil today with no change.
 

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Crossing a wire at 90 deg is usually not a problem. Look for wires that are close and run parallel to the signal wires.
 

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Discussion Starter #19
OK we tried a few more things including checking rotor phasing ( looked good ) , Moving the coil wire away from the MSD pick up, new cap and rotor ( after cutting holes in other one ). Still arcing and running a little rough.
He took the car for a about a 20 mile ride for a cruise night car show and pulled the plugs after getting home. The plug electrode and ground strap are bright chalk white like it has a brutal spark going on but the porcelain was showing a little rich. These were new plugs for this one ride. What would turn the tip white but show rich on the porcelain ?
 

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Discussion Starter #20
I should mention that the white on the ground strap goes about half way down the bend. The engine temp is also around 205 to 210 degrees.
 
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