1968-69 Charger vacuum lines removed from headlight switch (alternative)

[ncmiller1]

My 68 Charger had a vacuum leak at the headlight switch, and I decided to remove all headlight related vacuum lines from the cab.  I did this by buying 3V1-06 solenoid valves (x2, about $15 for the pair) and putting them under the battery tray.  

The below pictures document what I did, and they work great!  I essentially took the vacuum line coming out of the vacuum reservoir that usually goes through the firewall into the headlight switch and rerouted it to these solenoid valves.  I split the vacuum line so there is a line to each solenoid.  You can see in the pictures I attached the two solenoids together for organization, but they function separately; one controls the headlight door "close actuator" and the other controls the "open actuator."

Electrically, the solenoids are energized by the high beam or low beam wire (depending which one is powered).  I installed diodes in the leads from both the high and low beams to prevent them from back feeding each other, which I explain a little more below.  This keeps the headlight doors closed when the lights are off, and open when either the low or high beams are on.

I did run into an issue with the solenoid valves being threaded for BPT (British pipe thread) which meant it was pretty much impossible to find correct hose barbs, so I used NPT barbs instead.  The thread difference didn't allow the barbs to screw all the way in, but three full rotations combined with RTV there are no vacuum leaks and everything is very secure.  To remedy this, they do sell metric versions which may be easier to find parts for.  The "-06" designation of "3V1-06" is what indicates it is BPT, whereas the "-M5" in "3V1-M5" indicates the ports are threaded for metric attachments.

It's far from original, but if this solution works for anyone else hopefully the pictures help!

[ncmiller1]

The top picture shows the vent cap for one of the solenoid valves.  I tapped it to accept a hose barb and plugged the vent holes with RTV since this was going to be utilized as a "vacuum in" position.

The next two pictures show the fittings installed on the solenoid valves.  I connected the two solenoids by cutting the head off a bolt and screwing them together with a generous portion of RTV.

The fourth picture shows the whole unit put together, with filters installed on the two "vent" positions (old T-shirt material).  I screwed the two solenoids to some scrap metal as a bracket which made it easier to attach to the radiator support.

The fifth picture is everything hooked up and bolted into place under the battery tray.

[ncmiller1]

Below are poorly drawn diagrams.  The top picture shows the vacuum flowpath, both de-energized and energized, for the unit as a whole (both solenoid valves together).  The striped area represents the black part of the solenoid, the unstriped portion the white part.  When de-energized there is constant vacuum to the headlight "close actuator" and the "open actuator" is vented to atmosphere.  When energized, the vacuum path swaps with the "close actuator" vented and the "open actuator" under vacuum.

The bottom picture shows how I wired the solenoid.  I tapped both the high beam and low beam headlight wires, soldered in diodes (x2 part#1N4001, less than a $1 each) to each to prevent backfeeding the low beams when the high beams are on, or the high beams when the low beams are on.  I originally was going to skip the diodes and wire into the fog light wire, but with the Ron Francis wiring kit, the fog lights weren't on when the low and high beams were on.  Luckily this ended up working just fine.

[doctor4766]

Ingenious.

[TexasStroker]

Very cool!

[VegasCharger]

So with this set-up is it still possible to have the headlight doors open with the headlights being off?

[ncmiller1]

So with this set-up is it still possible to have the headlight doors open with the headlights being off?

It's not possible to have the headlight doors open with the headlights off because of the way I wired the solenoids.  Since the relays are energized by the power to the low/high beams, I'd have to wire a separate 12V switchable source to open the doors without the lights on.

[prothed]

Just bumping this post to add my congratulations to ncmiller1 for this solution.
I had previously considered something similar but found that the 3V1-06 valves would not do the job as standard - however, the modification shown in the post of adding a new outlet to the vent cap makes it all work! 

Two small points - To eliminate air/vacuum leaks I put some sealant between the two halves of the valve body so that the vacuum doesn't bleed down when the engine is stopped, and (although this is of no importance) the OP said that his valve outlets used BPT threads, whereas the identical valves bought here in the UK have US NPT threads.. Go figure.