spark jumping out of the wire??

I'm just getting my project running,, So far just a few test fires.
When we were cranking it over I noticed that spark was jumping out of the distributor where the the boot is for the the plug wire . I'm running a MSD 46,000 volt coil and a MSD-BTM- box. It jumps about 1" to the supercharger and it makes a loud "crack" when it dose it. The wires and plugs are new.
I know that electric follows the path of least resistance SO,, I'm thinking that I have a bad wire or plug. If the wire and plug were good it would be easier for it to go down the wire and jump the small distance across the
electrode at the plug.
It only does it when the engine is being cranked over not when it's running.
It seems find when it's running. But I know there is a problem that will be back to haunt me.
anyone know of anything that will make this happen other than a plug or
wire?

the cap and rotor are new, Mallory And the wires are new also Summit

When it jumps out it's like it is coming right out of the boot.
I was just thinking I could trade the parts with another cylinder and see
if the problem follows the parts?

reddevils86 said:

I'd do exactly what you plan on doing during troubleshoot but I will say I've had nothing but problems with mallory ignitions on my rx7 with a 350 in it. Granted its a chevy engine but from others Ive talked to with ford engines in em all recommended another brand could be bad luck or me being a retard but some food for thought

Click to expand...

I had no choice Mallory is the only company that makes a distributor to fit my 5.0 with a blower-(needed to use a crab cap)

and the rotor and cap are new