hello , this was exactly my previous post about efi clean source 12v . (electric nightmare , if you want to read )
BTW holley seems hidden what should be clear and simple . Take a look to holly sniper forum and you will see how many people are in the same lack of info about sniper . i think that if you need a forum only to solve issue .... mmm  ... this let me think dark clouds ! anyway  the only place you get 12v run and start is on the + side of coil ( the pink resistor wire become green/red at firewall until coil )  
Now the issue is this : do you have oem points  and condenser or you moved to pertronix 1  ? 
with pertronix you need full 12v and that's good because with a relay you can control run and start position.  
if you still have condenser that need 7/9 volts  can be not so easy to solve . The fact is that efi needs run and start both togheter , and old ford switch do not have this common spot .  BTW i have changed ignition switch couple years ago with conventional parts (rockauto ) and really don't know if internally is changed , cause i have 12 v run and start at pigtail just after the switch . Check again with multimeter this pigtail and the + side of coil when run and start  , .you should have juice all the time .  Check 12 v or more aftercrank , you should have 13/14  volts at battery (if not there is a problem )  . The fact you have 11 volt is not good . Bad grounds , weak alternator or regulator , wires cut and splice everywhere ... this the major issue . 
So... at the end the easy solution is move to pertronix 1 or 2  with correct coil and a relay . 
After that you will need a longer arm at throttle link because the pivot point is wrong . it snap ,  too much on/off at pedal make imposible to use and start from stop  (manual transmission ) 
hope it help . 
if you need info , jus ask 
bye 
 

Evan wrote:

Hey hope everyone is doing well.  I just picked up a Holley sniper system for my 66 mustang w 302. And mustang Steve cable clutch conversion. In the instructions it says to find a clean 12v ignition source. It must have 12v when cranking and in run position. And says not to connect it to the ignition coil or the starter solenoid. I’ve been look all over the car and can’t really find anything that’s what I need. On the.c terminal from the igition switch it’s like 11. Some volts in run and when cranking drops to like 9. I was thinking I may need to run a relay.  Is their anyone that has tackled this before. Any help would be appreciated. Thank you.

Evan.

Hmmmmmmmmmmm........could this be 'another' Mustang-guy' from the Greaaaaat state of California!?????
WELCOME to the coolest  Mustang board on the web!
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Welcome aboard!
6sally6 (I ain't-no-chick!)
 

I have put the Sniper "switched ignition pink" wire to the "A" terminal on the ignition switch and it works fine.

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Evan wrote:

While  I’m at it wiring up a relay should I just build a relay panel for future things like electric fans etc. as it looks like I’ll need one for my fuel pump as well.

Thanks.

Prolly a good idea. Definitely wanna look into upgrading the wiring on the headlights (hi & lo beams) and the horn fer sure.
6sally6
 

Evan wrote:

Hey guys I’m finally working on my wiring. As it took a while to get the rest of the parts I needed. I’m now about 4 wires away from start up and am on the pink wire to hook up. I pulled my ignition switch last night and wanted to confirm before I go hacking away at wires. The one I want to use to pull the 12v in run and start is terminal a from the starter switch which on the pigtail looks like it’s the yellow wire. Is that correct?

The yellow wire is 12 volt battery with stock 66 wiring. The red/green wire is made in Run/start. If you can tap that before the Pink resistor wire you will have 12VDC in run/Start, remember as BB stated during cranking voltage will drop.