Spark such way?

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Grounding the top of the spark plug will shut the spark off. Some old power equipment engines had a eyelet type spark plug wire and you'd flip over a piece of metal that would ground the spark plug, shutting the engine off.
 
Originally Posted By: yvon_la
Does a spark on spark plug go from head to sparkplug center core?would adding a ground on the head prevent spark?


Assuming the polarity of the head is true negative potential (and wire and tip is positive potential), yes, since electron current flow is from negative to positive.

Head bolts should provide a good ground from head to block.

Just curious, are you getting spark noise in your radio?
 
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The Whole engine is the ground .If the engine was isolated from the negative in the ignition circuit there wouldn't be a spark.
 
The "head" as you mention it sounds like the "side electrode" as many would consider it.

Traditionally, spark goes down the center tip, jumps the gap, and is grounded by the electrode/ head and "used up".

The first generation distributorless ignition systems sent the spark down the center electrode, jumped to the electrode, went through the shell and cylinder head to another shell, electrode, jumped another gap before it was "finished". The ignition coils' +/- were positive and negative compared to the rest of the vehicles' common ground.

Adding a ground to the tip would screw up the spark, for sure.

Plugs can short themselves out with carbon tracking on the insulator nose within-- carbon is a pretty good conductor and just has to be better than the air gap. This can also happen externally if your coil wire boots break down-- once electricity finds a path, it gravitates toward it again.
 
Originally Posted By: yvon_la
Does a spark on spark plug go from head to sparkplug center core?would adding a ground on the head prevent spark?


The head is already grounded by the bolts that hold it to the block. Somewhere there is a ground wire (negative) from the battery to the engine (at the block, or the head, or some bracket on the motor). Adding a ground on the head would have no effect.
 
Ok ty guys, as for :the head is already grounded via bolt !it depend if it's the part you want to ground is iron or aluminium. In most case the part made of aluminium is not properly grounded.
 
Originally Posted By: yvon_la
Ok ty guys, as for :the head is already grounded via bolt !it depend if it's the part you want to ground is iron or aluminium. In most case the part made of aluminium is not properly grounded.


Aluminum is a good conductor, and even if the head were made of aluminum, it would still be grounded to the block by the head bolts.

If you wanted the head to not be grounded it would require plastic head gaskets, plastic head bolts, and a plastic or rubber valve assembly and no one would try to build such a motor because it simply would not hold up to the stresses a motor has to handle.
 
The high voltage low current flow that the plug uses should go though the engine (head), the coil (or distributor's coil), the wires (or just the coil on plug itself), and the plugs, that's it. The low voltage high current input from the battery that gets converted to high voltage low current would go from battery, fuse box, and a bunch of cables.

Unless your existing wire is corroded, adding additional engine grounding wouldn't do anything.

p.s. Ground can have different meaning depends on how you look at things. On a waste spark the ground could be just the engine block / head, and the non "ground" electrodes of the spark plugs that connects to the coil pack could be labeled "positive" and "negative", etc. Ground is just a name given to a reference point in a system of "flow", like electrical current.
 
Originally Posted By: Chris142
My Jeep fires 3 plugs one way and the other 3 plugs the other way


A Bi-Polar Jeep?
smile.gif
 
Originally Posted By: yvon_la
Ok ty guys, as for :the head is already grounded via bolt !it depend if it's the part you want to ground is iron or aluminium. In most case the part made of aluminium is not properly grounded.


Whatever increased resistance is between the spark plugs threads and aluminum pales to the resistance in the plug's internal resistor and the plug wires. This doesn't really matter at 30K volts and milliamps.
 
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