So after spending time , effort and $$ smothing out the firewall I've come to the conclusion that the best location for the new wire bulkhead is right here:

couple of questions..........
1 - where was it before ?
2 - have you considered moving it down low, coming through the top of the toe board ? [passenger's side perhaps ?] doing that would keep your smooth firewall looking great !
at least that would be what i would do, after spending the time you did smoothing everything out.

OP's showing the same location as original.
Might be difficult after the smoothing work.
What harness is being used ? That could drive the decision on a bulkhead location, or may eliminate it.

The front end will be completely custom wired and most of the wires will likely come through in the drivers side wheelwell and follw the inner fender up to the front. But the main harnesses of concern are the two bulky ones for the Holley Terminator. The big "roadblock" is the heater - which occupies most of the space below the cowl and all the way to the right side.

In the attached photo they've picked the ideal spot BUT they obviously haven't got the stock heater in the car.

Ahh - so if I understand correctly, this is a custom build and you want to hide the harnesses for a clean appearance ?

I'd be thinking about using the RF wheelhouse for the Terminator harness, bringing it in through the apron or something like that.
If the car will never see rain or gravel roads, the Terminator components could likely be hidden in the wheelhouse.
Unless you go to a smaller aftermarket heater assy, the OEM heater is taking up valuable real estate.
You're in a tough middle ground between restoration (which implies stock-appearing) and customized to an aesthetic vision.

I'm thinking you should make sure everything works & is bug-free before drilling/cutting/finalizing.

Yes, trying to keep things clean and tidy. I really don't want anything on either the firewall or the inner fenders if I can help it. The ECU and MSD will likely go inside, The battery will be in the trunk and I intend to build a dustproof box to house the misc front end relays and electrical connections and I'll probably use the stock battery location for that.

As it is I consider the Terminator harness to be very "messy" but it is what it is. Don't really want to tear into that - at least not yet!



Everything is tested before install. The engine was fired with the whole EFI system installed prior to putting it in.

Couple shots of the firewall area . After feeling around behind the heater there seems to be a good amount of space between the back of the heater and the firewall to the left of the blower motor - just above the tunnel. Probably worth pulling the heater back out to have a look and if so to cut the holes.

When I re-wired my Challenger using a couple of Painless wiring kits, I mounted the fuse box under the dash and left of the glove box. I ran the cables to the front under the fenders to keep the wires out of the engine bay. Since I installed all the Racepak stuff it seems pretty cluttered again though

I filled my heater blower motor opening, any unused factory holes and bulkhead connector hole on my firewall and inner fenders. I also have my wiring running along the top of the inner fenders. My Racepak sensors are all piggy backed along my snout bars.

Though it was difficult, mine goes thru the passenger floor into the RF frame rail. Comes out just behind the motor plate. Also just did a small block turbo Duster. The lights, fan, and boost controller go thru the left fender well. The harness is attached to the fender bolts that are slightly longer. The main engine harness comes thru a grommet behind the wiper motor.
Doug

Some very helpful stuff ! Thanks for the photos - they're always helpful.

Tidy

if one considers routing the harness through the wheel house, it could be run through a piece of tubing welded to the firewall and uppermost part of the inner fender, to the core support [or wherever one wants to enter the engine compartment], thus being protected from road debris.

I'm past the welding stage !!!

how about using conduit connectors ?
i believe they use something like a compression fitting, and at one end, they have threads that use those 8 [?] pronged nuts to fasten to electrical boxes.
that setup could be "bolted" [zip tied, etc.] to the upper part of the inner fender in the wheel house area.
just tossing out a simple idea........

My F body has had the wiring in the fenderwell since 1990. Taped up well. Never an issue.
Doug

I have no issues with putting the wiring in the fenderwells. I don't think they'd need much in the way of protection - probably nylon wrap mainly to keep them together. And these to keep them in place:

i have used that nylon wrap material, and it's pretty tough stuff, good for many installations, as it comes in many sizes from 1/4" to [i believe] 2".
it's also very reasonably priced, cheap in fact, and it usually comes in 18ft lengths.
however, it takes a little practice to wrap around your wire bundle, especially if you are like me, being "all thumbs".
i terminate the ends with a piece of marine heat shrink tubing for good looks. not really necessary, but that's just me.
and it's WAY better looking than that cheap plastic, ringed, split loom that everyone seems to use too much of, everywhere under the hood.

I agree the nylon shrink wrapped looks really good.
Doug