MSD 6LS box and Holley Sniper.

OK I have the engine in this Olds. I have the sniper plumbed in from tank to Sniper. I have the fuel pump working and the screen for the sniper lights up. I setup a basic 350 with stock cam and no power adder,Idle speed set at 750 rpm. So just a basic tune to get it up and running. Here is where I'm having issues. It says to use the tach output from the MSD to the tach input on the sniper. I have done this and it shows no RPM's So it also says you can plug in a single purple wire into the green/purple wires and hook that up to the tach output as well. I have tried both ways and get no signal to the sniper that the tach is working. Now with that said the actual tach in the car is working. I guess my question is do I need to disconnect that tach to send a pure signal to the sniper. Is it possible that the in car tach is messing with the tach signal?

So out of curiosity I dumped some gas into the sniper and hit the key and it fired up. No issues. So its definatly the snipers lack on RPM signal that wont allow fuel to pass through it.
Anyone got any Ideas?

Here is the MSD 6LS wiring schematic.


Here is the Sniper schematics.

Connect tachometer to Snipers Brown wire, not the MSD tach output.
Use the MSD Tach output as the input to The Snipers magnetic pickup. manyal says there is a purple adaptor wire with connector in the box?
Change Ignition Type in the Software configuration.

Holley Video, wiring starts around 7:20 into the video.


Do not connect the Sniper Yellow wire to the CD Ignition coil.

I am not sure why the Sniper Yellow wire can not connect to the MSD Tach output?

If it was me, I would take advantage of the Snipers timing control. Lock the distributor advance, and get the rotor you can phase, or re-index the reluctor to pickup to get the correct phase index, then use the Sniper to trigger the MSD box.

451Mopar said:

Connect tachometer to Snipers Brown wire, not the MSD tach output.
Use the MSD Tach output as the input to The Snipers magnetic pickup. manyal says there is a purple adaptor wire with connector in the box?
Change Ignition Type in the Software configuration.

Holley Video, wiring starts around 7:20 into the video.


Do not connect the Sniper Yellow wire to the CD Ignition coil.

I am not sure why the Sniper Yellow wire can not connect to the MSD Tach output?

If it was me, I would take advantage of the Snipers timing control. Lock the distributor advance, and get the rotor you can phase, or re-index the reluctor to pickup to get the correct phase index, then use the Sniper to trigger the MSD box.

Click to expand...

Thanks for the info I watched several videos too but most seem to be just short of what I need to know. I will check out that brown wire tomorrow. The problem is this is an LS so there is no distributor and the 6LS does all the spark control. I have done 2 sniper setups in 2 mopars just never did one on a car with a CD box. I tried the purple wire to the MSD box Yellow tach output and got jack squat.

Putting the tachometer on the sniper tach output will prevent anything related to the tach to mess with the signal into the sniper. I hear some of the tachometer that do rpm sweep when powered on create a bunch of triggers to the sniper.
The MSD Green/Purple connects to the distributor (or crank trigger pickup only.)
The MDS Tach Output connects to the Sniper purple wire of the green/purple twisted wires.
Seems Yellow wire not used at all in that configuration.

451Mopar said:

Putting the tachometer on the sniper tach output will prevent anything related to the tach to mess with the signal into the sniper. I hear some of the tachometer that do rpm sweep when powered on create a bunch of triggers to the sniper.
The MSD Green/Purple connects to the distributor (or crank trigger pickup only.)
The MDS Tach Output connects to the Sniper purple wire of the green/purple twisted wires.
Seems Yellow wire not used at all in that configuration.

Click to expand...

The tach in the car does sweep when you turn the key on then goes back to 0. So maybe that is it. I'll check it out.

From what I have been reading you can ground the tach output wire from the MSD for 5 seconds to disable tach sweep. Does that sound correct?

Cut the wire from the tach loose and connected the purple wire to the tach lead from the MSD. I now have a tach signal. But the voltage drops well below 10 volts under cranking. Its as low as 8. So Im charging the battery and hoping it will fire off once its charged.

If not the battery, check the battery cables and connections. Bad battery cables/connections can cause voltage drop when cranking the engine (high current load.)

The battery is definitely weak. I have body to battery ground,body to block, frame to engine and main battery ground to block. Pretty sure it’s grounded well.

OK got it running. But have one issue I need to deal with tomorrow something I overlooked. But anyhow took a couple pictures of the setup today looks pretty cool for an LS.