1988RedT2
1988RedT2 MegaDork
11/11/21 2:59 p.m.

1966 Chevy II Nova hardtop, Holley Sniper EFI install in progress.  Fuel pump relay will be mounted under the hood.  Fuel pump lives in the tank. 

What's the best way to secure and protect wiring?  Should I run inside, through the passenger compartment, then through a hole in the trunk?  Clamp it every so often under the car?  To me, under the car just sounds like trouble.  What says the hive?

alfadriver
alfadriver MegaDork
11/11/21 3:12 p.m.

If it were me, I would try to keep the wire inside more than outside.  (also keep in mind the length also means you may want to run the wire a little larger.... but that applies for both scenarios)

1988RedT2
1988RedT2 MegaDork
11/11/21 3:26 p.m.

In reply to alfadriver :

Agree.  I bought as much of the accessory equipment that Holley makes in an effort to make this easier.  The wire they have provided is pretty beefy, 12 AWG, I would guess, in a length that will easily make it back there.

pres589 (djronnebaum)
pres589 (djronnebaum) UltimaDork
11/11/21 3:29 p.m.

Because I never do this stuff by hand anymore, I used this voltage drop calculator;

https://www.southwire.com/calculator-vdrop

It's recommending a 14ga wire assuming a 5A draw from the pump.  I took that number from an orrifice so grain of salt.  You might want to step up to 12 since 14ga isn't the most common stuff *in my experience, YMMV*.

Seconding alfa's suggestion of 'more inside than outside'.  The route though the trunk sounds smart.  I might even put it inside some small diameter rubber or vinyl tubing for added protection.  Don't forget the fuses.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/11/21 7:03 p.m.

I added an isolated camping battery to an old station wagon using heavy wire.  I just bought a 10' section of 1" PVC pipe.  I heated it with a hot air gun and bent it to follow the up-turns in the frame and ran the wire inside that.  Some pipe straps and self-tappers took care of holding it in place.  Totally overkill, but remarkably easy to do.

I did realize that the pipe ended up filling with water so I drilled a couple holes in the bottom for drains.  For your wiring, you could get away with 1/2" PEX which is much easier to bend.

stuart in mn
stuart in mn MegaDork
11/11/21 7:24 p.m.

I think all US cars of that era ran the wiring to the rear of the car inside the body - either under the door sill plates, or under the carpet next to the driveline tunnel.  I wouldn't put it underneath.

1988RedT2
1988RedT2 MegaDork
11/12/21 1:45 p.m.

Yup.  I've run it over to the driver's side where all the wires from the fuse block come through the firewall, fed it back in there, and ran it down the DS sill to behind the back seat, where a convenient hole puts it within easy reach of the fuel pump pigtail.

Thanks all!

1988RedT2
1988RedT2 MegaDork
11/12/21 1:46 p.m.
Curtis73 (Forum Supporter) said:

I added an isolated camping battery to an old station wagon using heavy wire.  I just bought a 10' section of 1" PVC pipe.  I heated it with a hot air gun and bent it to follow the up-turns in the frame and ran the wire inside that.  Some pipe straps and self-tappers took care of holding it in place.  Totally overkill, but remarkably easy to do.

I did realize that the pipe ended up filling with water so I drilled a couple holes in the bottom for drains.  For your wiring, you could get away with 1/2" PEX which is much easier to bend.

Curtis,

Even though I didn't use your suggestion, I'd like to say that I think it's a damn fine idea!

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/13/21 12:39 p.m.

In reply to 1988RedT2 :

All good, man.  It was overkill for a fuel pump wire 

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