Well, lets suffice it to say that electrical arcs are not supposed to happen in uncontrolled circumstances on vehicles - I wouldn't classify an arc as "sparks flying", maybe thats what he meant.
Spark plugs are a controlled, calculated, internal arcing process, and thus are not a very good analogy.
Uncontrolled electrical arcs occur when a power source is either too close to ground, is improperly insulated, or both - It is not caused by a "bad ground". If the ground was bad, it would not have arced in the first place.

The OP sure is silent, with the little we know it appears that he either has a bad + connection or a dead/dying battery incapable of supplying proper voltage to start the vehicle.

 

That was also my point. Yes the starter is grounded to the block but are the ground connections the engine good? If not, its not going to work. It is possible.

 

Very possible, PH - Thats the problem we get when people post requesting help, and give little info to go on, and no follow up.
From what he said, I couldn't see any reason why the engine grounds would be disturbed doing a tranny install, but who knows ?

 

The point I was trying to make was that the statement about sparking being a short was not the only thing that causes sparks. When CURRENT and VOLTAGE is high enough, arcing will occur and, not just to ground but, it will happen from wire to wire, contact to contact, in a fuse, inside a switch, in a relay contact etc. Here's a video of an arc and note the distance apart of this arc. http://205.243.100.155/frames/mpg/500kV_Switch.mpg

What you were referring to in regards to close proximity and poor insulation is a short condition. A great example of this is shorting ignition wires where, they short to the block or other ignition wires. Here we have super hi-voltage in close proximity to ground along with a dielectric breakdown of the insulation where, it arcs through the insulation into a neighboring wire or ground. That's a short condition and, is positive to negative and, is only one type of condition that causes sparks.

It is very common to see arc over in a SPST switch under the right conditions. Hi VDC through a switch that has a thick carbon buildup or heavy oxide layer on the contact will arc and kill the contact. That's in-line and not in close proximity to ANY ground source and, it has nothing to do with insulation nor dielectric properties either as a matter of fact. Under loading conditions, the circuit will draw excessive current due to higher resistance. As a result, it will violently burn through through the oxide and carbon layer and arc over inside the switch thus killing it in most cases.

It's not about how close in proximity a power source is to a ground- that is only partially true and, your forgetting it's CURRENT and VOLTAGE that causes that to occur not just proximity. That was the point of my comment and, being an engineer and having worked around electronics of all kinds for 20+ years, I felt that was the basic 101 that anyone could understand.

In a micro chip layout, the traces are microns apart and they don't arc over. Same with PCB traces- they are very close together and don't arc over unless; the voltage and current exceeds the dielectric resistance and spacing requirements per design specs.

I thought the above comment was misleading to readers and inaccurate so, I felt that it needed to be cleared up that's all. Didn't mean to step on your toes so, sorry if it came off that way.

Chris M