Holley Sniper on 700 hp big bock

1967 Cuda said
Yes, wiring is one of my biggest concerns. The fact that the wires for the sniper unit come out the front side near the distributor where are all the plug wires run causes me some concern. I am going to run Firecore spark plugs wires and try to route the sniper wires as far away from them as I can, but there will be areas that will be close. Did you run any shielding on the sniper wires on any of your installs. If so, what did you use?

Keep any wire running to the EFI - aside from distributor wires which may give you zero choice in the matter - at least 2-3" away from all spark plug wires.

1967 Cuda said
My other concern is that my battery is going to be mounted in the trunk and it will be a longer clean power wire from the sniper to the battery. Do you think I should be concerned on this long span?

Just make sure the wire is large enough for its intended current. For a trunk to engine compartment run, you may want to subtract 2 to 4 from the usual wire gauge recommendation for shorter runs.

Also, don't forget the ground wires, which should also be upsized and grounded straight to the battery for best results.

1967 Cuda said
In regards to the fuel system, I went with the whole Holley setup and have the tank and upgraded 400 LPH in-tank pump, so I should be good there. I did have a question on your response above regarding the fuel line. I am about to run stainless hard line for the fuel system and am debating 1/2" or 3/8". The Holley site says 3/8" inside diameter line is required. I am guessing that is equivalent to 1/2" O.D. tubing? What have you used for fuel line in the past? You also mentioned above a single pressure line from the tank. The XFlow unit I am installing requires an external regulator, so I think I need to run a return line to the tank as well?

Thanks again for your above response and insight!

External regulators with EFI (or any pump capable of delivering EFI levels of pressure even run with a carb) always need a return line. You don't want to use a deadhead arrangement as that will send line pressure to the moon upstream of the regulator. When using an in tank pump, you can mount the regulator next to (or even inside!) the tank and use a very short return line, although this arrangement is more likely to have vapor lock and a vacuum reference would be a pain. For normal automotive hard line you can ignore the wall thickness for sizing.