Why two vacuum lines from distributor?

[FrazerJames]

Ah, I think I found where to tap into - the wiring from the key switch to the ignition coil should be run and start, which I think you mentioned above, but now that I’m getting everything to sink in it’s coming together.

This diagram helped a lot.

http://forum.garysgaragemahal.com/file/n97055/B2109C9E-7743-4F2D-B5C2-07F3EDC6D391.jpeg

Correct and running it to trigger a relay shouldnt have an adverse effect on your ignition system. It may be what I try on my setup if I dont feel like dropping the column on my truck to find the wire at the ignition switch itself.

I got a lot of this set up last night thanks to your help! I do have one question though - do you think I should put an inline fuse between the battery and the relay? Right now I plan to have it run straight to the battery.

[Gary Lewis]

I got a lot of this set up last night thanks to your help! I do have one question though - do you think I should put an inline fuse between the battery and the relay? Right now I plan to have it run straight to the battery.

I doubt you were asking me, but I vote YES! Put a fuse between the battery and the relay.

[FrazerJames]

I doubt you were asking me, but I vote YES! Put a fuse between the battery and the relay.

Easy enough!! :)

[FrazerJames]

Yeah, they do mention a relay as an option in the instructional videos. It’s beyond my know-how at the moment, though. I have real trouble wrapping my head around electrical - I just don’t do it enough to retain the science of it.

Having this one choke wire be hot for crank/run would be insanely lucky... I’ll likely have to find another source, but I’d prefer not to have to run it from the inside of the cab.

Well the factory choke wire was only hot after the engine was cranked up and running. That way you can go to accessory mode and listen to the radio without the choke opening up fully.

On the relay its not really that hard. On a 5 pin relay you have pins 30, 87, 85, 86, and 87A.

Pin 87A which is the middle pin is normally hot then when the relay is activated pin 87A loses power, this pin if you decide to use the AC cut out function of the sniper will require your compressor clutch wire to clutch come from this pin 87A.

Pin 30 would be your power wire being triggered. It can be power or ground, in the case of the sniper for AC cut out it would be battery hot.

Pin 87 would be your triggered output going out to what is being powered or grounded by the relay. In the case of the AC cut out this would be left empty. In the case of powering up your sniper this would go to your key hot on the sniper wire.

Pin 85 is one leg of the trigger. In the case of the AC cut out this would go to output #6 which Holley uses grounds for triggers. In the case of the key on relay for the sniper this terminal would be grounded.

Pin 86 is the other leg of the trigger circuit. This one in the case of the AC cut out would go to battery hot for the sniper to apply ground to activate cutting the AC off. In the case of a key hot relay this pin would be the key hot circuit you are using that is hot in crank and run position.

If it helps below is the wiring schematic I created for my truck for my auxiliary fuse/relay box. The sniper related relays are numbered R4, R5, R6. My plan is to not use a relay for the key hot trigger seeing as I have no more relays if I follow through with using R7 and R8 for auxiliary roll bar lights (two spots/two floods). I could get a larger fuse/relay box but then it comes with way too many relays/fuses. Only way I could add an extra relay for the sniper key hot would be to try and run 400W worth of halogen lights off a single 30/40A relay. In theory I should be able to as at 12.8v nominal battery voltage 400w worth of lights is 31A and at 14.0v which is what the 3G regulator is set to, 14.3V to be exact drops the amperage requirement down to 27A/28A. So I should be able to run both sets of lights off one single 40A 5 pin relay.

But maybe this wiring diagram can help you with planning out your hook up as far as the sniper goes.

I think I’m all set up thanks to your help Rusty!

Last thing - the biggest advantage of setting up that A/C cutoff is to have more power at WOT, correct? Otherwise it isn’t doing much, right?

[Rusty_S85]

I got a lot of this set up last night thanks to your help! I do have one question though - do you think I should put an inline fuse between the battery and the relay? Right now I plan to have it run straight to the battery.

If you mean for the main power feed to the sniper yes you should have a fuse there to protect the sniper circuit. The trigger wire you dont have to put a fuse in it since it is fused via the ignition switch itself but it wouldnt hurt if you wanted to fuse the wire as well.

I think I’m all set up thanks to your help Rusty!

Last thing - the biggest advantage of setting up that A/C cutoff is to have more power at WOT, correct? Otherwise it isn’t doing much, right?

The cut out you will have to use a laptop to set the specs for it cause not all sniper installations will hit 100% on the TPS. So what you will have to do is look at your TPS go wide open throttle and if it shows say 85% then I would set the cut out trigger to be 75% That way it will trigger around 90% of full throttle if that makes sense.

The point of the cut out would be to take the AC clutch drag off the engine in a passing situation to give you more power and acceleration to pass someone. If you are using a sanden style compressor if you upgraded to late model system then you wont really notice a difference as the sandens dont eat up a lot of power. If you have a old dealer installed unit using a old York compressor then you will notice a difference as they take a few hp away from the engine to turn.

Out side of that the AC cut out relay will just sit there deactivated majority of the time, its why you have to use 87A pin the center most pin as that pin is hot all the time that way you will have a complete circuit, the sniper typically provides a ground for most of these features so youll need your trigger side to have a ignition hot, another plus to having a ignition hot relay as you can use the same trigger to provide a trigger for the other relays so all the sniper has to do is simply apply a ground when the requirements are met to activate.