H4 Heavy Duty Wiring Upgrade

[bigmuddy]

Tobtech, trust me you are wasting your time arguing...

 

[Steve83]

...this isn't the venue to teach a class.

You noticed that? Good.

The short answer is, relays are available in all sizes and specs...

So are switches.

...and I purchase the correct ones for the application.

So did Ford. But in many cases, they engineered their own switches, and then bought those switches from companies that could meet Ford's specs. Do you ever test your switches to make sure they meet your specs?

...it would melt within 24 hours with the wrong switch.

So if it lasts 68 years, and is worth ~20x as much now as when it was originally sold, it's probably NOT the wrong switch. Especially a modern copy made with better materials, better engineering, and more testing.

With relays I also control the gauge and length of the 12 volt feed into the relay.

Ford did that with the switch & headlights.

I make sure its sufficient and its also dedicated to that circuit.

Yeah, they did that, too.

The OEM headlight switch pulls its 12V from a feed that is common with the feed to the fuse box and fed from the battery, starter or alternator and depends on the quality of that connection.

So yours is NOT coming from the battery, and does NOT depend on the quality of your connections? Are you a better engineer than Ford hired in the 50s through the 70s? Are you spending more on testing on your designs than they did on theirs? Are the vehicles you designed & built lasting as long as Ford's?

I guess I went to a different class than you because I'm sticking with Ford's designs whenever possible. And even today, they don't build headlight circuits the way you're describing. Why do you think that isn't?

Tobtech, trust me you are wasting your time arguing...

Right - it's a discussion forum. He should be discussing.

 

[Yeller]

Glad this is a discussion forum.

Some 2024 heck even some 2010 wiring diagrams need reviewed. The switch does nothing but send a message to a relay controlled by the BCM in today’s vehicles.

 

[gnpenning]

The engineers from back in the day used what was available and made the best of it. As time and most people have progressed, we have the luxury of using better ways of doing things. Good thing or we would still be using rocks for wheels.

 

[73azbronco]

Relays move the high current out of the switch to a more direct/shorter path. I did the WH light mod, thought it wise even though I used LED lights (which suck and Ill replace later). All the current for my headlights and KC lights are contained in front of the battery. Everything behind that is small gage wire.

No, you do not have to do this. But on a 50 year old wire loom living in the southwest? Yeah. You do not have to have a 347 either.

 

[ntsqd]

Can I have a 408 instead of the 347?
Ignore nvrstk, he's going to want a 460 SBF instead.....


For headlights I never use a fuse in the relay power supply wire. I use a self-resetting breaker instead. At 70+mph on a moonless night in BFE blinking headlights are better than no headlights. You can likely guess how I know this.

Those of you with the HEI ignition conversion should also be running that power pig via a relay.

 

[Steve83]

The engineers from back in the day used what was available and made the best of it.

Not back in the '66-77 days that we're talking about. Back then, Ford actually BUILT many of the parts that its engineers designed.

 

[73azbronco]

ah the good old days.

 

[gnpenning]

Not back in the '66-77 days that we're talking about. Back then, Ford actually BUILT many of the parts that its engineers designed.

Aaaaanñnddd that's what was available back in the day and that's what they used.